Having first trained in karate as a youth, at age fourteen he started boxing and won his first Finnish Amateur Championship title in 2004.

In July 2014, it was announced that Tatli will challenge Richard Abril for the WBA lightweight world champion title on September 20 in Helsinki.

Olli Mäki lost a featherweight championship match to Davey Moore in August 1962 at the Helsinki Olympic Stadium.

On 6 May 2017, Tatli was slated to defend his EBU lightweight belt against the highly rated Francesco Patera in his native Finland.

[9] On 20 April 2019, Tatli fought rising prospect Teofimo Lopez, who was ranked #4 by the WBA, WBC and IBF and #5 by the WBO at lightweight.

[12] He was scheduled to fight for the EBU lightweight title against Gianluca Ceglia in May 2020, but the bout was postponed to take place on 8 August 2020, due to the COVID-19 pandemic.