By the end of October, Abraham made the WBO aware that he could fight Smith again in the 2015. In December 2014, a deal was reached for the rematch to take place. The fight would take place on 21 February 2015 at the O2 World Arena in Berlin. With another win, Abraham was hoping to set up a fight with Felix Sturm. With 9,000 fans in attendance, the fight went the full 12 rounds as Abraham won via points on all three scorecards (116-112, 117-111 twice). Abraham was mostly dominant during the fight when he unloaded a barrage of power punches, and spent some time against the ropes, covering up, to keep himself becoming fatigued. After the fight, Smith praised Abraham, "I felt I left it all in there tonight, I'm not going home with any or many regrets. He shook me once or twice, he was better tonight (than the first fight)." The fight averaged more than 4 million viewers SAT1 in Germany.
Abraham fought Robert Stieglitz (47-4-1 27 KOs) for the fourth and final time on 18 July 2015 at the Gerry Weber Stadium, Nordrhein-Westfalen, Germany. The fight was billed as 'Final Showdown'. The WBO ordered the fight on 26 February, giving both camps 90 days to reach a deal. A deal was reached by both camps on 9 April. Although having a 3–1 lead against Stieglitz, Abraham promised to win via KO to cement his place as the number 1 super-middleweight. Prior to the fight, Abraham made plans to continue his boxing career for a further two more years before considering the possibility of retirement. In an interview, he said, "I will not lose. I plan on continuing my career for at least another two years and then retiring along with my coach and my world championship belt. " He also made plans to possibly unify the division. Abraham won via TKO in the sixth round. Stieglitz was knocked down in round 4 once but managed to pick himself back up. Abraham was ahead on three judges scorecards at the time on stoppage (48-46, 50–44, 49-45).
On 7 October 2015, Matchroom Sport announced that negotiations were done for Abraham to defend his WBO world title on 21 November against 33 year old British boxer Martin Murray (32-2-1, 15 KOs) at the TUI Arena in Hanover. Murray was still looking for his first world title after being stopped late by world middleweight champion Gennady Golovkin earlier in the year in what was his third world title challenge. Murray was on a three match winning streak since. The fight went full 12 rounds as Abraham won via split decision (116-111, 115–112, 112-115). Murray lost one point for holding in round eleven, which did not affect the outcome. Abraham praised Murray during the post fight interview, "I trained hard, have shed blood and sweat. I was technically and tactically the better boxer. But I didn't box against a punchbag. He is a world-class fighter, who put in a good fight and you have to acknowledge that."
His family members call him "Avo", short for Avetik. Abraham married his wife Mary, then a Yerevan State University student, in 2015. The wedding took place in Armenia and was not publicized; he informed media of his marriage six months later. His younger brother Alexander is also a professional boxer, and his older brother Christian owns a furniture shop.