Mitrita, 23, joins fromRomanian side Universitatea Craiova after putting pen to paper on a multi-year contract.
NYCFC paid an $8.5 million transfer fee, MLSSoccer.com reported, citing a source with knowledge of the deal. That would be the third-highest transfer fee ever paid by an MLS club, after Atlanta United's purchases of Pity Martinez (reported between $14M-$17M) and Ezequiel Barco (reported $15M).
Hehas already joined the team at their preseason training camp in Abu Dhabi.
"I'm very happy to be a part of this team and I'm looking forward to getting started," Mitrita said in a team statement. "It is a great joy for me and I will do my best to play at a high level. I want to make everyone who believes in me proud that we were able achieve this transfer.
"I know this is a good group and I'm going to a club where young players can develop and grow. The team has a very good coach who has experience with lots of great clubs in Europe.
"MLS is a very strong league, otherwise I would not have come here. I don't want to say too much now in terms of goals and objectives -- I prefer to see how things progress. I want to take things step-by-step and give my all in every match and we will see what we can achieve together."
A longtime Romania youth international, Mitrita has made five senior appearances for his country since making his debut in March of last year.
"Alexandru is a very talented attacking threat who can score goals and create chances when running at the opposing team," said NYCFC sporting director Claudio Reyna. "At almost 24, he's part of an exciting younger generation coming out of Romania.
"He comes to New York during a stage in his career where he's extremely motivated to make the next step after recently breaking into the Romanian national team. He possesses an innate desire to win and is focused on becoming an important player for our Club as we challenge for the Supporters Shield and MLS Cup.
"He was an important player at his previous club and very well-liked by an amazing and loyal fan base. Our fans will immediately notice the personality he carries on the field and they'll really enjoy watching him play for NYCFC."
Nicol: David Villa a class act on and off the pitch
Steve Nicol reflects on the impact David Villa has had on Major League Soccer after announcing his departure from NYCFC after four seasons.