Apart from her group's activities, Sunny has participated in numerous side projects including original soundtracks, television variety shows, musical acting and radio hosting.

[7] After the outbreak of the Gulf War, Sunny and her family returned to South Korea and settled in Jongno-gu, Seoul.

She transferred to Starworld agency, where her father worked as a manager, and was to debut in a duo group called Sugar.

[16] In 2009, Sunny released two songs—a solo track "Finally Now" for the interactive movie Story of Wine and a duet "It's Love" for the MBC's drama Heading to the Ground, with Girls' Generation's member Taeyeon.

[17][18] During 2009 and 2010, Sunny was a co-host for MTV Korea television music program The M with SS501's Kim Hyung-jun and 2AM's Im Seulong.

The reality program narrated a journey of a group of South Korean celebrities who were brought together to work and experience the agricultural and rural life.

Sunny found the recording process to be initially difficult, stating that because Miranda was such a "charismatic" and "strong" character, it was hard to express "with just [her] voice" as it would have been "a different story if [she] was showing the actions".

[29][30][31][32] During 2012–2013, Sunny was cast in her first musical, Catch Me If You Can, based on the true story and life of a con man named Frank Abagnale.

Shin Yeong-seon from The Chosun Ilbo noted on Sunny's ability to understand the character and praised her well-portrayal of Brenda's "exaggerated cuteness and flippant acting".

[40][41] In November 2014, her solo song, "First Kiss", was released as a part of musician Hwang Sung Je's Project Super Hero series.

[45][46][47][48] In April 2015, Sunny's voice was featured on indie-band Roof Top House's debut single "Heart Throbbing".

The purpose of the show is to create a one-on-one vocal battle between veteran singers in Korea and talented amateur vocalists.