Smith first began his career with Brooklyn (A) of the New York–Penn League by allowing two runs, one earned, in one inning of work against the Staten Island Yankees on June 21. He was named one of the top 20 prospects in the New York–Penn League by "Baseball America". When Duaner Sánchez was hurt during a taxi cab incident in 2006, Mets general manager Omar Minaya considered recalling Smith to the Majors. But ultimately, the Mets traded for Roberto Hernández and Óliver Pérez to give Smith more time in the minors. On March 24, 2007, after a strong spring training, it was announced Smith would be on the Mets' 25-man roster. On April 1, 2007, Smith made his major league debut. He struck out one (Preston Wilson) and walked one (Albert Pujols). He also gave up a single to David Eckstein. Smith earned his first major league win on April 24, 2007 after coming on in relief in the 12th inning. Smith enjoyed much success in the beginning of 2007, but began to tire and was sent down to the minors at mid year. Smith was with the Mets for all of the 2008 season, enjoying varied success. He went 6–3 in 63.3 innings with an ERA of 3.55.