Lambo, whose 31 homers in 117 games are tied for the most in all of Minor League baseball, had his contract selected and will be in St. Louis for Tuesday's start of a three-game series against the Cardinals. He will be making his Major League debut, after 669 games and 2,451 at-bats in the Minors.
Outfielder Alex Presley, hitting .264 in 29 games, was optioned to Triple-A Indianapolis to make room for Lambo on both the 40-man and 25-man rosters.
The arrival of the 25-year-old Lambo will answer the hopes of fans, who have been beating the drums for him for weeks.
Will it also answer Pittsburgh's need for more offense? Time will tell, but it's worth noting that Lambo cannot supply the most needed element of right-handed power. As another left-handed hitter, he joins the southpaw brigade of Pedro Alvarez and Garrett Jones.
Lambo has split the 2013 season evenly between Double-A Altoona and Indianapolis, combining for 97 RBIs and a .284 average in addition to the 31 homers in 117 games.
The production marks a rush back into the Bucs' plans by Lambo, who went on the team's 40-man roster upon his 2010 acquisition from the Dodgers in the deal that also landed James McDonald, then played himself out of that status.
In 2011 and '12, Lambo hit a combined 16 homers in 164 games.
A fourth-round selection of Los Angeles in the 2007 First-Year Player Draft, the 6-foot-3, 210-pound Lambo has limited experience at first base but has spent most of his playing time as a corner outfielder.
Tom Singer is a reporter for MLB.com and writes an MLBlog Change for a Nickel. He can also be found on Twitter @Tom_Singer. This story was not subject to the approval of Major League Baseball or its clubs.