“The quality of the league has improved,” he said. “I think we’ve seen that — the quality of the players coming in to play here, the quality of the homegrown players, as you’ve seen in the U.S. team at the World Cup. Top players want to play in good-quality leagues, and M.L.S. is a real option now, where five to 10 years ago it might have been seen slightly different.”

Lampard, who had played for Chelsea since 2001, is the Blues’ record-holder for appearances (429), goals (147) and assists (90). He will most likely go out on loan this fall because New York City F.C., which is operated by the Yankees and Manchester City of England’s Premier League, will not begin play in M.L.S. until March.

Lampard was Chelsea’s captain when it won the Champions League in 2012 and England’s captain for its final game at the World Cup in Brazil this summer. He played in almost 600 Premier League games and made more than 100 appearances for his country, including trips to the past three World Cups.

His signing, to a two-year contract, comes almost two months after New York City added the Spanish striker David Villa from Atlético Madrid. Villa also has a Champions League title on his résumé, with Barcelona in 2011. The moves give the club an experienced attacking core to build around, with room for one more marquee signing under M.L.S.’s sometimes complicated roster and salary structure.