The Cubs, continuing to rework their starting rotation, announced the signing of free-agent left-hander Paul Maholm on Tuesday.
The two sides agreed to terms on a one-year contract with a club option for 2013.
FOXSports.com reported news of the negotiations Monday.
Maholm, 29, went 6-14 with a 3.66 ERA for the Pirates last season, ending the year on the DL with shoulder trouble. The Pirates paid him a $750,000 buyout rather than exercise his $9.75 million option.
The Cubs have dramatically overhauled their rotation this offseason, trading right-hander Carlos Zambrano for righty Chris Volstad and acquiring lefty Travis Wood in the Sean Marshall deal.
Maholm joins the group of new starters at a time when the team is still talking about trading its No. 1 pitcher, right-hander Matt Garza.
The Mariners, Red Sox, Orioles and Pirates were among the other teams that showed interest in Maholm.
The Orioles are close to signing another lefty, Wei-Yin Chen.