Following his transfer from AS Trencin, Adi scored a goal in his F.C. Copenhagen debut against FC Vestsjælland on 25 August, despite not having his work and residency permit. In January 2011, Adi, then 20 years old, was invited for a trial by Ajax for the second time.
On 13 May 2014, Adi went on loan with the option to buy to Portland Timbers of Major League Soccer. He made his debut coming on as a substitute against Columbus Crew and got the game tying assist, a feat which earned him a start in the following match. In his first start for the club, on 28 May 2014 against Chivas USA, Adi scored his first and second goals for the club. On 7 June he received his second start and scored two goals in the first half against Real Salt Lake. Adi was signed permanently by the Portland Timbers on 23 June 2014. He became the club's fourth ever Designated Player. On 8 April 2017, after scoring a penalty kick against the Philadelphia Union, Adi became the Timbers' all-time leading goalscorer, with 46 goals.
Adi was traded from Portland Timbers to MLS expansion side FC Cincinnati on 30 July2018 for a deal worth up to $1,000,000 in allocation money. He played the remainder of the 2018 season with FC Cincinnati in the United Soccer League ahead of the club's move up to Major League Soccer. Adi started in the first three matches of FC Cincinnati's inaugural MLS season. However, in the third match on 17 March, he was injured after a collision with Larrys Mabiala late in the first half, and was subbed out at halftime. He remained on the bench with a left ankle injury the next two matches. At approximately 3:45am on 31 March 2019, Adi was pulled over by the Ohio State Highway Patrol and cited for operating a vehicle under the influence of alcohol, speeding, and not possessing a valid driver's license. According to the police, Adi was driving 102 mph in a 65 mph zone, showed a blood alcohol content of 0.124 in a breathalyzer test, and possessed only a Ukrainian driver's license. Adi was suspended by FC Cincinnati and entered MLS' Substance Abuse and Behavioral Health program. Adi was cleared from suspension on 24 April and began practicing with the team the following day; however, his minutes remained limited as his ankle was still recovering. He made his first appearance since the injury in the final 11 minutes of a San Jose Earthquakes match on 4 May. He played another 26 minutes as a substitute in the following two matches. On 25 May, Adi started for the first time since 17 March and played a full 90 minutes. Adi scored his first goal of 2019 in a U.S. Open Cup match against Louisville City FC on 12 June. He scored his first goal in the 2019 MLS season on July 13 against the Chicago Fire. It gave FC Cincinnati the lead and victory, 2–1. Following a tumultuous season with Cincinnati, Adi was waived by the club on 17 January 2020, ahead of the 2020 season.
Columbus Crew
On 27 January 2020, Columbus Crew SC announced that it had claimed Adi off the Major League Soccer Waiver List.
International career
Adi was called up to Nigeria's U23 team twice in 2011. He was also called up to the senior Nigeria squad to face Egypt in a 2017 Africa Cup of Nations qualifier in March 2016 but did not play.
