[1] Born and raised in Iowa to Patrick and Cheri Gilman, Thomas moved to Nebraska to attend Skutt Catholic High School in Omaha.

[11][3] In the postseason, he claimed runner-up honors at the Big Ten Championships to Ohio State's Nathan Tomasello[12] and became an All-American with a fourth-place finish at the NCAA's.

[3] His first loss came at the Big Ten Championship semifinals by two-time NCAA runner-up Nico Megaludis, and he came back to claim third place at the tournament.

[17] As the top–seed at the NCAA's, Gilman was on a dominant with two majors and a fall over rival Nick Piccininni to make the semifinals, but was defeated by the eventual winner of the championship Darian Cruz, getting thrown to the consolation side of the bracket.

[26] At the 2017 World Championships, Gilman opened up with big wins over 2016 European Continental runner–up and two–time Cadet World Champion from Ukraine Andriy Yatsenko and 2017 Asian Continental medalist from Iran Reza Atri, before defeating 2017 Dave Schultz Memorial runner–up Nodirjon Safarov and stunning 2014 Asian Games Gold medalist from North–Korea Jong Hak-jin to astonishingly making the finals of the tournament.

[27] In the finale, Gilman's 15 match win–streak was broken by 2017 Asian Continental champion from Japan Yuki Takahashi, claiming the 2017 World Championship Silver medal.

[30] He then claimed a bronze medal from the Pan American Championships, after falling to 2017 U23 World Champion from Cuba Reineri Andreu in the semifinals and bouncing back in the third–place match.

[34] Gilman started off the year competing overseas, claiming an Ivan Yarygin Golden Grand Prix bronze medal and placing 15th at the Dan Kolov – Nikola Petrov Memorial.

[35][36] After coming back to the United States, Gilman claimed runner–up honors from the US Open, losing to Daton Fix in the finals but not before beating Nathan Tomasello.

[50] In his last event of the year, Gilman was unable to keep his unbeaten streak and was defeated by 2019 Bill Farrell Memorial champion Seth Gross via criteria in December.

[60] As the Russian kept advancing on the bracket, Gilman was pulled into repechage to compete on August 5, dominating Gulomjon Abdullaev from Uzbekistan and '19 Asian champion Reza Atri from Iran in order to capture the bronze medal for the United States.

[63] Different from his 2017 finals, Gilman emerged victorious over '21 Asian Continental finalist Alireza Sarlak on October 4 in order to acclaim the World Championship, becoming the first 57 kilogram American competitor to do so.

[66] Gilman claimed the spot to represent his country at the 2022 World Championships for the fourth time in his career, taking out Vito Arujau twice in a row at Final X Stillwater.

[69][70] Gilman will usually try to be as physical as possible, controlling the center with his strength and walking down and pushing his opponent while overwhelming him with heavy hand fighting until a takedown opportunity opens up.