Alex Gonzalez drove in the game's only run.
Lester (5-0) gave up only a single to Mark Teahen in the second inning. The 22-year-old left-hander walked four and struck out four. He became the first Red Sox rookie starter to win his first five decisions since Aaron Sele won his first six decisions in 1993.
Jonathan Papelbon retired the side in order in the ninth inning for his 28th save to complete the one-hitter and boost the AL East-leading Red Sox to their second straight one-run victory.
It marked the first one-hitter for Boston since May 25, 2001 when Hideo Nomo did that against Toronto.