[3] Ham previously competed in the MMA promotions Deep, Smackgirl, Jewels, Road FC, UFC, and Rizin.

[10] In Japan, she is occasionally nicknamed "Arale-chan", in reference to her looks outside of the ring bearing resemblance to the character Arale Norimaki from the manga series Dr.

[13][14][15][16] Ham was defeated by Miku Matsumoto via triangle choke submission on May 13, 2007 (2007-05-13) at clubDeep Toyama: Barbarian Festival 6.

[17][18] Ham rebounded back from her first loss with a unanimous decision victory over Ayumi Saito on September 6, 2007 (2007-09-06) at Smackgirl 2007: Queens' Hottest Summer.

[20][21] On February 14, 2008 (2008-02-14), Ham participated in the Smackgirl World ReMix Tournament 2008 Opening Round, where she defeated Saori Ishioka by unanimous decision.

[42] On March 6, 2011 (2011-03-06), Ham faced Anna Saito in a mixed martial arts rules match at Gladiator 15: GI 2.

[51][52] On April 21, 2013 (2013-04-21), Ham faced pro wrestler Ryo Mizunami at Gladiator: Dream, Power and Hope.

[59][60] In early November 2014, Seo Hee Ham signed a four-fight contract with Ultimate Fighting Championship to join UFC's Strawweight division.

[64] After nearly a year away from the company, Ham returned to face Cortney Casey on November 28, 2015 at UFC Fight Night: Henderson vs. Masvidal.

[66] After briefly considering retirement, Ham signed with Road FC where she became the atomweight champion with a victory over Mina Kurobe.

[75] It was reported that Ham will face Denice Zamboanga in the quarter-final of the ONE Women's Atomweight Grand Prix at ONE Championship: Empower on May 28, 2021.

[79] Due to the controversy the decision stirred, the bout was placed under review but the ONE Championship committee left the result standing.

[80][81] Ham was scheduled to face Stamp Fairtex in the semi-final bout of ONE Women's Atomweight Grand Prix at ONE Championship: Next Generation on October 29, 2021.

[95] Ham had her first professional kickboxing match at CMA Festival 2: Ikuhisa Minowa Debut 10 Anniversary Tournament on July 23, 2007 (2007-07-23), where she defeated former Smackgirl Open Weight Champion Megumi Yabushita by unanimous decision.

[97] At Jewels 7th Ring on March 19, 2010 (2010-03-19), Ham had an exhibition match against Shoot boxing rising star Rena Kubota.

[98] Ham earned another unanimous decision victory over Japanese fighter Miyu Matsui on April 25, 2010 (2010-04-25) at Gladiator 6, winning the CMA KPW Lightweight Championship.

She defeated Emi Fujino and Mina in the opening rounds, but lost to Erika Kamimura via unanimous decision in the tournament final.

[105][106] Ham defeated pro-wrestler Stalker Ichikawa by left high kick KO at Gladiator 10 on October 3, 2010 (2010-10-03).