In 2011, T-ara released the song "Roly-Poly". It became the best-selling single of the year on the "Gaon" chart in South Korea. The group also became popular in Japan. Later that year they signed a contract with agency J-Rock to manage their sales in Japan. The contract was for USD 4.7 million. This was the most any Korean girl group had made in a foreign market at the time. T-ara went on to make a Japanese studio album called "Jewelry Box". This album reached number one on the "Oricon" weekly charts in Japan. Also in 2011, T-ara released the Korean album "Black Eyes". It lead to three number ones songs in a row. These were "Cry Cry", "We Were in Love" and "Lovey-Dovey".
In 2012, T-ara had a drop in popularity. The group was accused of disagreements and problems with one another. Soon after, Hwayoung left T-ara. Areum did the same a year after. After these issues, T-ara's albums and songs had mixed success in South Korea. As a result, T-ara changed their focus to China. In 2014, they made a cover of the Chopstick Brothers' song "Little Apple". After focusing on China, T-ara became one of the most popular K-pop groups in the country.
In 2017, the contracts of Soyeon and Boram were set to expire. On the other hand, Qri, Eunjung, Hyomin and Jiyeon had extended their contracts. This would reduce the members of the group from six to four. T-ara had intended to make one more album as a six-member group. However, a conflict with their management lead to a delay and it did not happen. T-ara's next release was as a four-member group. This was the EP called "What's My Name?" which was released in June 2017.
T-ara was formed by the record label Mnet Media, which is now known as Stone Music Entertainment. The original members of T-ara were Jiae, Jiwon, Eunjung, Hyomin and Jiyeon. They trained together for three years before their debut. The group's name is based on the word "tiara". The idea for the name was that they would be "queens of the music industry". Their first song came before their official debut as a group. It was "Joheun Saram" for the soundtrack of the "Cinderella Man" television show. One month before their official debut, Mnet Media changed some of the members of the group. Jiae and Jiwon left T-ara in early June 2009, and were replaced by Boram, Soyeon, and Qri. Then in early July 2009, T-ara was moved from Mnet Media to Core Contents Media. Core Contents Media is a subsidiary of Mnet Media, and is now known as MBK Entertainment.
T-ara made their debut in July 2009 on the "Radio Star" talk show. Their first performance was on the "M Countdown" music show a few days later. It included the songs "Geojitmal" (or "Lies") and "Norabollae?". The performance had negative reviews by those who watched it. Some felt was that it was lip-synced and had an "elementary school" appearance. In response, the group decided that future performances would be live. In September 2009, T-ara made the song TTL "(Time to Love)" with the boy band Supernova. It became the first number one song for both groups and topped many online charts. A month later, T-ara and Supernova made the follow up song "TTL Listen 2".
T-ara made their first studio album in November 2009, with the name "Absolute First Album". Core Contents Media held a survey to have the public help choose which song would be the title track. The choices were "Bo Peep Bo Peep" and "Cheoeum Cheoreom" (처음처럼, "Like the First Time"). Of the 9,000 people who took the survey, 53% chose "Cheoeum Cheoreom". However, "Bo Peep Bo Peep" was chosen as the title track. It made it to number four on the "Gaon" chart. "Cheoeum Cheoreom" made it to number ten. T-ara performed these songs live on the "Music Bank" television show on 4 December 2009. At the 24th Golden Disk Awards, T-ara won Rookie of the Year along with girl group 4minute.
The group won their first music show award with "Bo Peep Bo Peep" on the first day of 2010. The song went on to win five awards in total. T-ara intended to follow up with promotions for "Cheoeum Cheoreom" as well. But these had to be canceled in January 2010, as Soyeon got sick with H1N1. Later that month, T-ara had a cameo appearance in two episodes of the television show "God of Study".
In February 2010, the group re-released their debut album under the title "Breaking Heart". The digital release was on February 23. The two lead singles were "Neo Ttaemune Michyeo" (너 때문에 미쳐; "I Go Crazy Because of You") and "Naega Neomu Apa" (내가 너무 아파, "I'm Really Hurt"). "Neo Ttaemune Michyeo" made it to number one on the "Gaon" chart and "Naega Neomu Apa" made it to thirty-one. T-ara performed on the same day on "M Countdown". They went on to win three awards for "Neo Ttaemune Michyeo". The physical release of the album was March 3. It made it to number two on the weekly "Gaon" chart and number thirty-five on the yearly chart. T-ara performed "Naega Neomu Apa" on music shows in March and early April 2010.
In July 2010, T-ara added Hwayoung as a seventh member. The stated reason was to give other members some relief from their heavy schedules. It would also allow each member to be away for solo activities from time to time. In November 2010, the group starred in the third season of the reality show "Hello Baby". Later that month, T-ara released "Wae Ireoni". It is the lead single for their first extended play, which is called "Temptastic". "Temptastic" was released in December 2010, along with the single, "Yayaya". T-ara performed on "Music Bank" on December 3 with their new seventh member Hwayoung. They later won awards for "Wae Ireoni" and "Yayaya" on "M Countdown".
T-ara made their second extended play (or EP) in June 2011. The title is "John Travolta Wannabe". It made it to number three on the Gaon Album Chart. The EP's single, "Roly-Poly", made it to number two on the Gaon Digital Chart and number one on the Korea K-Pop Hot 100 chart. It became the highest-selling song of 2011 in South Korea. "Roly-Poly" won the award of Best Music Video at the 3rd Melon Music Awards. T-ara also won Singer of the Year at the 1st Gaon Chart Awards. They were also nominated for Best Dance Performance by a Female Group and Song of the Year at the 13th Mnet Asian Music Awards.
In August 2011, T-ara made a limited edition re-issue of "John Travolta Wannabe" with the title "Roly-Poly in Copacabana". The title track is a eurodance remix of "Roly-Poly". It was given the name "Roly-Poly in Copacabana" after the song "Copacabana" which was popular in the 1980's in disco clubs. The album made it to number three on the Gaon chart. The song made it to number forty-five on the Billboard Korea K-Pop Hot 100 chart. The group then performed the song on the "Music Bank" television show.
T-ara made a Japanese version of "Bo Peep Bo Peep" in September 2011. It made it to number one on the "Oricon" weekly chart. This made T-ara the first non-Japanese girl group to make it to number one on the "Oricon" chart. The song also made it to number one on the Billboard Japan Hot 100 chart.
In November 2011, T-ara made their third EP, "Black Eyes", which made it to number two on the "Gaon" charts. The album followed the release of the song "Cry Cry", which made it to number one on the Billboard Korea K-Pop Hot 100. "Cry Cry" also won two first-place awards on "M Countdown". The music video for "Cry Cry" had a billion Korean won budget and a thirty-minute drama story line. The group made their second Japanese song, a remake of "Yayaya" from their "Temptastic" EP, in November. It made it to number seven on the "Oricon" charts and number six on the Billboard Japan Hot 100.