When Topić hit the sixth grade, he and his father started to watch a lot of boxing on TV.

[5] Also a professional graphic designer, Topić graduated from William Paterson University with a bachelor's degree in Fine Art.

Topić quit his full time job in graphic design in order to focus on his fighting career.

[11] In 2017, Topić fought Tum Sityodtong in the main event for Triumph Kombat 3 at Madison Square Garden.

[12] On July 8, 2017, he defeated Paul Barber in the United Kingdom to become the Muay Thai Grand Prix Lightweight Champion.

[13][14] On March 2, 2018, Topić defeated Travis Clay by unanimous decision to win the Friday Night Fights Lightweight Championship.

Topić made his promotional debut on May 12, 2018, at ONE Championship: Grit and Glory, defeating Stergos Mikkios by unanimous decision.

[18] Looking to bounce back, Ognjen Topić next faced Saemapetch Fairtex at ONE Championship: Roots of Honor on April 12, 2019.

[19] Riding on the momentum of a decision victory over Petchtongkam Bangkok-Alaigym at Lumpinee Stadium, Ognjen Topić faced Alaverdi Ramazanov at ONE Championship: Dreams of Gold on August 16, 2019.

However, being outsized, Topić found himself being floored 3 times en route to a first-round TKO loss.