Commissioner David Stern announced the change late Sunday.
Garnett's absence was not unexpected after Coach Doc Rivers' comments following a 98-90 victory against San Antonio earlier in the day.
"I don't see him playing Tuesday or Wednesday and I don't see him playing in the All-Star Game, either," Rivers said after the contest.
The 6-foot-11 inch, 13-year veteran missed his seventh straight game Sunday because of an abdominal strain.
The 6-foot-11 inch Wallace, who is in his 12th season out of North Carolina, will be making his fourth NBA All-Star appearance.
This season, he has averages of 12.9 points and 7.3 rebounds in 47 games.