Mikaelian amassed an 18–0 record during the next four years,[1] before being booked to fight Daniel Alejandro Sanabria for the vacant WBO International cruiserweight title on 5 September 2015, the first regional championship of his career.

[9] On 28 April 2017, it was announced that Mikaelian would face Krzysztof Włodarczyk in an IBF cruiserweight title eliminator.

[11] Mikaelian faced the #1 seed of the 2018 World Boxing Cruiserweight Super Series Mairis Briedis on 10 November 2018, in the main event of an ESPN broadcast card, which took place at the Credit Union 1 Arena in Chicago, Illinois.

[13] Mikaelian faced Jesse Bryan for the vacant WBC International cruiserweight title on 12 December 2020, following an eighteen-month absence from the sport.

[14] Mikaelian next faced the former WBA interim cruiserweight champion Youri Kalenga on 12 February, this time coming back from a fourteen-month absence from the sport.