Chicago (AFP) - Jon Lester says Chicago has some of the most passionate fans in Major League Baseball and he is fully committed to bringing the Cubs their first championship season since 1908.
"I got a good sense of how crazy these fans are about their Cubs baseball," Lester said.
"It's a huge honour to be part of this organization. We fully buy in, and we take on the responsibility of trying to bring this city a World Series."
The Cubs formally introduced the 30-year-old pitcher at a downtown Chicago news conference on Monday.
The Cubs did not provided details of his contract but the US media had reported that it is a six-year deal worth $155 million.
"This signing really marks a transition of sorts for the Cubs, the start of a period where we are clearly very serious about bringing a World Series to the Cubs and the people of Chicago," president of baseball operations Theo Epstein said.
"It's a great day for our fans. They've been so patient with us, incredibly patient, over the last few years and they truly deserve a pitcher and a person of this calibre to call their own."
Lester went 6-4 with a 2.35 earned run average for the Oakland Athletics after he and outfielder Jonny Gomes were acquired in a trade-deadline deal from Boston for outfielder Yoenis Cespedes.
Lester has a 116-67 won-loss record with a 3.58 ERA over his nine-year career.