Yusmeiro Petit will replace him in the rotation, manager Bruce Bochy said Monday. Bochy met with Lincecum (10-9) on Sunday about the decision.
"He's fine," Bochy said before his team opened a four-game home series with Colorado. "He's going to work on some things. It's no problem with him."
Lincecum, the two-time NL Cy Young Award winner, is coming off the second-shortest start of his career Saturday at Washington. He was tagged for six runs, four earned, on six hits with four walks in 2 2-3 innings.
He pitched his second no-hitter against San Diego in less than a year June 25, but has lost four out of his last five decisions with just one win in his last seven starts. That comes after a four-start winning streak beginning with the no-hitter.
Lincecum received a $35 million, two-year contract in late October to stay with the Giants, his only franchise. He is earning $17 million this season.
The 30-year-old Lincecum has experience pitching in relief, going 1-1 during the team's 2012 run to its second World Series title in three years. He pitched the Game 5 World Series clincher at Texas in 2010 as the franchise won its first championship since moving West in 1958.
The Giants drafted him 10th overall out of Washington in 2006 and quickly promoted him to the majors in May 2007.
Lincecum -- the Cy Young winner in 2008 and `09, when he won 18 and 15 games, respectively -- went 10-14 with a 4.37 ERA and 193 strikeouts over 32 starts last year, his third straight season with a losing record.
Petit will pitch Thursday afternoon's series finale with the Rockies at AT&T Park. Whether Lincecum stays in the bullpen and Petit in the rotation beyond Thursday will depend how they each do.
"We'll make that call on the next start after this Petit start," Bochy said.
Bochy announced second baseman Marco Scutaro is done for the season with his recurring back problems and resting at home in Florida. He played in only five games.