The Mets' new star outfielder was introduced at a news conference at Shea Stadium two days after he signed a seven-year, $119 million contract.
Beltran, who came to the Mets from the Houston Astros, had been one of the hottest free agents on the market.
The Mets beat out the Astros, Chicago Cubs and New York Yankees for his services.
"This is great, this is a dream come true. I'm happy to be a part of this. I will do the best I can," Beltran said.
"Of course there will be expectations of me and I also expect a lot from myself too. In this game, when you do well people love you. When you do bad, people boo you. That's in every park."
Beltran hit .267 with 38 home runs and 104 RBI for Kansas City and Houston in 2004.