Highest Rated Korean Dramas of 2021

[Last Updated on October 21, 2023]

One of the things that make 2021 a special year for Korean dramas is “Squid Game’s” global success at an unprecedented level. The show became Netflix’s biggest series of all time in terms of hours viewed within 28 days of release, pulling in 1.65 billion hours. And with its three wins at the SAG Awards, it is no doubt the most successful Korean drama in 2021. But that’s when we talk about K-dramas being adored internationally.

It’s a different story when we look at TV ratings, which are the basis of our rankings of the highest rated Korean dramas of 2021. Forget about international popularity because the lists below reflect the viewing behavior of these shows’ main target audience. Read on to find out which dramas pulled in millions of viewers all over South Korea while they were airing.

Historical or period dramas dominate the ranking in both the cable and free-to-air (non-cable) categories—a total of seven out of 20! SBS and tvN are the leading networks with 5 and 6 series in the top 10 ranking, respectively.

In a stunner, JTBC has no representative in the top 10, which is really a surprise considering that it is home to the most-watched cable drama in 2020 (“The World of the Married”) and 2019 (“Sky Castle”). Each of the three ‘minor’ or lesser known cable channels, meanwhile, managed to put at least one show in the list.

We also have multi-season dramas gaining ground, which could lead to a game-changing event in an industry where one-season format has been the norm for decades.

(Methodology explained after the three rankings.)

Highest Rated Korean Dramas 2021: Free-to-Air Top 10 by Ratings

Ratings can be percentages of households, adults 18-49, or any defined group watching a given show. In South Korea, Nielsen mainly reports ratings in terms of households. A 10% rating means that an estimated 10 out of every 100 households throughout the country watched the given drama when it was airing. The remaining 90 households either watched something else or did not watch TV at all. 

10. River Where the Moon Rises

Average Rating: 7.6%

Peak Rating: 10.0%

Average + Peak: 17.6%

“River Where the Moon Rises” (KBS2) was one of the dramas struck hard by a pressing concern during production in 2021. But despite introducing a new male lead—Na In-woo replacing Ji Soo over bullying and sexual abuse allegations—and re-shooting more than 10 episodes, the series managed to maintain a 7 to 8 percent rating throughout its run. Both Na In-woo and his co-star Kim So-hyun received praise for their moving performances, a compliment reflected in their nominations for a Baeksang arts award.

9. The Veil

Average Rating: 8.3%

Peak Rating: 9.8%

Average + Peak: 18.1%

MBC had been struggling to obtain decent viewership for its dramas until “The Veil” came out. The series became a “savior” for the broadcaster in terms of ratings. With a total production budget of 15 billion won (US$12.1 million), the network must have been thankful that its investment paid off to an acceptable degree. Namgoong Min stars as a top National Intelligence Service agent in a story based on the winner of the 2018 MBC Drama Screenplay contest.

8. Lovers of the Red Sky

Average Rating: 9.0%

Peak Rating: 10.4%

Average + Peak: 19.4%

The 8th highest rated Korean drama of 2021 is another historical series, “Lovers of the Red Sky” (SBS). Did you know that it was helmed by the director of the hit fantasy romance “My Love from the Star” and the Baeksang-winning sageuk “Tree with Deep Roots”? Starring Kim Yoo-jung and Ahn Hyo-seop, the novel-based drama tells the fateful encounter of a painter and an astrologer who fall in love and find themselves painfully entangled in politics.

7. The King’s Affection

Average Rating: 8.0%

Peak Rating: 12.1%

Average + Peak: 20.1%

The seventh place also goes to a historical drama—a tale of switched identities and the love that comes after. In “The King’s Affection” (KBS2), Park Eun-bin pretends to be the crown prince of Joseon and hides her true identity after the death of her twin brother. But that is easier said than done, especially when she falls in love with her royal tutor, played by SF9’s Rowoon. The series premiered with a modest six percent viewership and went on to double this number during its finale.

6. Royal Secret Agent

Average Rating: 8.1%

Peak Rating: 14.0%

Average + Peak: 22.1%

The fourth sageuk in this list (and there is one more!), “Royal Secret Agent” (KBS2) stars Kim Myung-soo as a royal inspector who conducts undercover investigations into the corrupt practices of Joseon government officials. Although this job entails risks and serious battles against the bad guys, the show is less dark and more humorous. That style definitely worked, seeing that its five percent viewer rating in the first episode nearly tripled in the finale.

5. The Red Sleeve

Average Rating: 11.0%

Peak Rating: 17.4%

Average + Peak: 28.4%

Making it to the top 5 highest rated Korean dramas of 2021 is “The Red Sleeve,” the most watched historical series and the biggest sleeper hit in free-to-air television last year. Also based on a novel, it follows the romance between a Joseon King, played by Lee Jun-ho, and a royal court lady, portrayed by Lee Se-young. It also just started with a modest 5-6 percent rating but when it entered its third week, there was no stopping it from becoming the most successful drama of MBC in 2021.

“The Red Sleeve” earned seven nominations at the 2022 Baeksang Arts Awards including Best Drama and Best Director. It is the second most-nominated series behind “Squid Game.”

4. Taxi Driver

Average Rating: 12.6%

Peak Rating: 16.0%

Average + Peak: 28.6%

Lee Je-hoon played the titular role in this SBS action-filled drama that was inspired by real-life heinous crimes committed in Korea. But he is no ordinary taxi driver as the ride aims to avenge the suffering of passengers whom the law has failed to protect. The series obtained a double-digit rating right off the bat, although one can say it partly benefited from the popularity of its megahit predecessor, which also has a place in this list.

3. One the Woman

Average Rating: 13.5%

Peak Rating: 17.8%

Average + Peak: 31.3%

The third highest rated Kdrama in 2021 is the comedy “One the Woman” (SBS), about a prosecutor who loses her memory due to an accident and wakes up with a new identity. Lee Ha-nee plays this character and her exact look-alike, the much belittled daughter-in-law of a wealthy family. The beauty queen-turned-actress seemed to have chosen her recent projects very carefully, considering that her previous series “The Fiery Priest” and film “Extreme Job” achieved huge success in 2019.

2. The Penthouse Season 3

Average Rating: 17.1%

Peak Rating: 19.5%

Average + Peak: 36.6%

1. The Penthouse Season 2

Average Rating: 22.2%

Peak Rating: 29.2%

Average + Peak: 51.4%

The second and third seasons of “The Penthouse: War in Life” (SBS) are the top two highest rated Korean dramas of 2021. The immensely popular series that started in 2020 tells the story of the residents of a luxury penthouse apartment whose lives start to crumble when a young girl falls to her death in the exclusive apartment. Due to some similarities, many viewers could not help but compare it to “Sky Castle”—the most watched Korean drama in 2019—but “The Penthouse” is more intense, leaning heavily into makjang or overly dramatized elements.

Check out this summary before you proceed to the next ranking:

Highest Rated Korean Dramas 2021: Cable Top 10 by Ratings

10. Bossam: Steal the Fate

Average Rating: 6.0%

Peak Rating: 9.8%

Average + Peak: 15.8%

MBN’s only drama in 2021 rounds out the top 10 in the cable category. Produced as the channel’s 10th anniversary special series, “Bossam: Steal the Fate” surely did not disappoint. It started with only 2-3 percent viewership but went on to become the highest rated K-drama ever broadcast by MBN, unseating previous title holder “Graceful Family.” ‘Bossam’ refers to a customary practice in Joseon where a widow is kidnapped and forced to become the wife of the kidnapper.

9. Show Window: Queen’s House

Average Rating: 6.0%

Peak Rating: 10.3%

Average + Peak: 16.3%

“Show Window: Queen’s House” features no big names in its cast but with a riveting story about love and betrayal, it pulled off a highly successful run and wound up as Channel A’s most successful series of all time in terms of viewership. It barely hit 2 percent in its first week but it went on to cross the 10 percent mark in its final episode, which made it the biggest sleeper hit cable drama last year.

8. Love (ft. Marriage and Divorce) 1

Average Rating: 7.6%

Peak Rating: 9.7%

Average + Peak: 17.3%

Starring Sung Hoon and Lee Ga-ryeong, “Love (ft. Marriage and Divorce) Season 21” (CSTV) is a melodrama that follows three successful women as they navigate unexpected troubles in their happy marriages. Despite its rating success, many reviews online are not happy about the series. TV Chosun nonetheless thought it’s only right to make two sequels, a decision that proved to be a good one later on. Season 3 premiered in February 2022 and has so far shown that it can be as successful as the first two seasons.

7. Mine

Average Rating: 8.2%

Peak Rating: 10.5%

Average + Peak: 18.7%

Seventh placer “Mine” (tvN) centers on two women, played by Lee Bo-young and Kim Seo-hyung, in a conglomerate family who try to find their true selves and deal with injustice. More than a series that gives a glimpse into the lives of an uber-rich family, this show tells a compelling story of women coming together to protect each other and gain the freedom to live and love as they please. It was penned by the screenwriter of “The Lady in Dignity,” the highest rated Korean cable drama in 2017 in terms of peak rating.

6. Jirisan

Average Rating: 8.4%

Peak Rating: 10.7%

Average + Peak: 19.0%

“Jirisan” (tvN) is one of those big dramas that feature not only A-list actors but also celebrated and award-winning behind-the-scenes stars. Director Lee Eung-bok (“Mr. Sunshine”) and writer Kim Eun-hee (“Kingdom”) joined forces to depict the story of dedicated rangers of the Jirisan National Park. Jun Ji-hyun and Ju Ji-hoon headlined the series as among the rangers who protect the park and the countless visitors who climb through the mountain every year. Although “Jirisan” did not achieve ratings as high as the eponymous mountain, it impressively secured a double-digit viewership on episode 2 and consistently enjoyed decent ratings throughout its run.

5. Hometown Cha-Cha-Cha

Average Rating: 9.5%

Peak Rating: 12.7%

Average + Peak: 22.2%

The fifth highest rated Kdrama of 2021 is “Hometown Cha-Cha-Cha” (tvN), starring Shin Min-ah as a big-city dentist who opens up a clinic in a small seaside village. There, she meets a jack-of-all-trades (Kim Seon-ho) who becomes involved in her life in more ways than one. The romantic series became a hit not just in Korea but also abroad as reflected in streaming data from Netflix. It ranked seventh out of the 10 most viewed Korean dramas on Netflix last year as listed by Forbes.

4. Vincenzo

Average Rating: 10.4%

Peak Rating: 14.6%

Average + Peak: 25.1%

Also making it to the said Forbes’ list is fourth placer “Vincenzo” (tvN). In this series, Song Joong-ki played a Korean-Italian mafia lawyer on a mission to recover tons of gold in a basement of a commercial building in Seoul. When an evil conglomerate illegally takes ownership of the property, he sets out to win a legal battle not only to retrieve the treasure but also to give justice to the tenants of the building. The much-loved drama is a superb thriller with lots of comedy breaks.

3. Love (ft. Marriage and Divorce) 2

Average Rating: 9.2%

Peak Rating: 16.6%

Average + Peak: 25.8%

“Love (ft. Marriage and Divorce) Season 2” (CSTV) enjoyed high ratings like its first season. But it did so with a modest start despite the success of season 1. The show consistently saw improved ratings in almost every episode until it concluded with a record-breaking double-digit viewership, now ranked as among the 10 highest ratings of all time in Korean cable dramas.

2. Hospital Playlist 2

Average Rating: 12.0%

Peak Rating: 14.1%

Average + Peak: 26.1%

The runner-up spot in this list goes to “Hospital Playlist 2” (tvN), the lone medical series in these rankings of the highest rated Korean dramas of 2021. The story revolves around five doctors, told in the signature directorial style of Shin Won-ho, the award-winning director behind “Prison Playbook” and “Reply 1988.” Season 2’s second place finish is due to its consistent ratings in the 10-14 percent range. Its first episode is currently the highest rated drama premiere of all time on tvN.

1. Mr. Queen

Average Rating: 12.6%

Peak Rating: 17.4%

Average + Peak: 30.0%

And now for the top spot, we have “Mr. Queen” (tvN), a historical drama about a top chef who one day finds his consciousness trapped in the body of a Joseon Queen. Starring Shin Hye-sun and Kim Jung-hyun, the series is now the seventh highest rated Korean drama on cable TV in terms of peak ratings, joining the ranks of “Crash Landing on You” and “The World of the Married” in the all-time Top 10. It marks the return of a tvN drama to the no. 1 spot, which was occupied by JTBC dramas in the last two years.

Here’s another summary for cable TV:

Overall Top 20 by Viewers

While it makes little sense to compare the ratings of free-to-air and cable shows side by side, we can still directly rank them together in terms of total viewers nationwide. In Nielsen’s vocabulary, this number equals the average number of people watching a show in any given minute while it airs. So here is the overall Top 20 highest rated Korean dramas in 2021, based on the PEAK total viewers achieved by the drama:

RANK	SERIES (CHANNEL)	PEAK VIEWERS (BY MILLIONS)	DATE AIRED
1	The Penthouse S2 (SBS)	5.601	3/27/2021
2	Mr. Queen (tvN)	4.749	2/14/2021
3	Hospital Playlist 2 (tvN)	3.853	9/16/2021
4	Vincenzo (tvN)	3.841	5/2/2021
5	The Penthouse S3 (SBS)	3.778	6/4/2021
6	Love (ft. Marriage and Divorce) S2 (CSTV)	3.344	8/8/2021
7	Hometown Cha-Cha-Cha (tvN)	3.237	10/17/2021
8	One the Woman (SBS)	3.235	11/6/2021
9	Taxi Driver (SBS)	3.117	4/17/2021
10	The Red Sleeve (MBC)	2.749	12/25/2021
11	Jirisan (tvN)	2.586	10/24/2021
12	Mine (tvN)	2.429	6/27/2021
13	Royal Secret Agent (KBS2)	2.323	2/9/2021
14	The King’s Affection (KBS2)	2.003	12/14/2021
15	The Devil Judge (tvN)	1.994	8/22/2021
16	Bossam: Steal the Fate (MBN)	1.940	7/4/2021
17	Love (ft. Marriage and Divorce) S1 (CSTV)	1.913	2/14/2021
18	Lovers of the Red Sky (SBS)	1.865	9/14/2021
19	The Veil (MBC)	1.814	9/24/2021
20	River Where the Moon Rises (KBS2)	1.747	2/23/2021

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Did you find these rankings useful? See also our definitive list of the 50 best Korean dramas since 2009 and the highest-rated K-dramas of all time.