Overbay, who'll turn 37 on Jan. 28, is a left-handed hitter with 13 years of experience in the Majors. Last season with the Yankees, he had 14 homers, 24 doubles and 59 RBIs with a .240 average in 142 games.
The Brewers also signed corner infielder Mark Reynolds, a right-handed hitter, to a Minor League deal on Friday in an effort to shore up the first base position.
"It's a position where we may have to mix and match with Overbay, Reynolds, Juan Francisco. We've got numbers now to work with and guys can come into camp and be competitive," Brewers general manager Doug Melvin said.
"We know what Lyle has done before and we know what Mark Reynolds has done and so we'll look at it and see how it all shapes up six weeks later."
Overbay's career began with the D-backs followed by two years with Milwaukee in 2004-05. It was with the Brewers that Overbay hit his big-league stride with 16 homers, 87 RBIs and a .301 average in '04 and 19 homers, 72 RBIs and a .276 mark in '05.
Before the 2006 season, with Fielder ready to take over at first base full-time, Overbay was traded to the Blue Jays where he spent five productive seasons. In '06 with the Blue Jays, he reached career highs with 22 homers, 92 RBIs and a .312 average.
And now with Fielder long gone, he's back to help fill what has been a troublesome position for the Brewers.
"Francisco and Reynolds are power guys, Lyle is probably a little better overall hitter," Melvin said. "He brings experience to the clubhouse, he's a pretty good defender. Obviously, he's older and he can come off the bench. He brings some things to us."
In his 13 years, Overbay has compiled a .267 average with 147 homers, 342 doubles and 640 RBIs in 1,466 games. He's also played for the Pirates and Braves.
"I didn't think we'd be able to sign both Reynolds and Overbay, but sometimes the situation with two guys doing it, you might get some production," Melvin said.