To replace Pearce on the 25-man roster, the Red Sox recalled first baseman and outfielder Sam Travis from Triple-A Pawtucket.
Pearce left Friday's 4-1 loss to the New York Yankees after popping out in the second inning. Red Sox manager Alex Cora said Pearce was suffering from back spasms and added that Pearce "felt numbness in his legs."
In 29 games this season, the 36-year-old Pearce is hitting .180 with one home run and nine RBI. Pearce sees the bulk of his playing time against left-handed pitching, and he has been used at first base, left field and designated hitter at various points this season.
Boston acquired Pearce in a trade with the Toronto Blue Jays last season, and he was a huge part of the Red Sox's success down the stretch and into the playoffs.
In 50 regular-season games with the Red Sox last season, Pearce hit .279 with seven homers and 26 RBI. Pearce then hit .333 with three home runs and eight RBI in Boston's World Series win over the Los Angeles Dodgers, and he was named World Series MVP.
After his strong showing in the World Series, Boston signed Pearce to a one-year contract in free agency.
Pearce landing on the IL is significant since the Red Sox also placed first baseman Mitch Moreland on the IL this week. As a lefty, Moreland was half of the platoon at first base with Pearce.
With both Pearce and Moreland on the shelf, rookie Michael Chavis is in line to see the bulk of the playing time at first base, while Travis will figure into the mix as well.
Travis has appeared in two games this season, and in 54 career MLB games over three seasons, he owns a .252 batting average with one home run and eight RBI.
Meanwhile, Chavis is a Rookie of the Year contender, as he is hitting .263 with 10 homers and 27 RBI in 36 games this season.
Boston will need continued production from Chavis as it enters Saturday's clash against the New York Yankees 8.5 games behind the Yanks for first in the AL East.