Oswalt spent his first 10 big league seasons with the Astros before spending the last four years with the Phillies, Rangers and Rockies. Berkman, meanwhile, played a dozen seasons in Houston before moving elsewhere for the final three years of his career. Though Oswalt last pitched with the Rockies and Berkman last played with the Rangers, the pair will sign one-day contracts prior to the ceremony and then officially retire as Astros.
"We are honored to celebrate the careers of Lance and Roy, two of the best players in Astros history," said president of business operations Reid Ryan. "Both were elite players and among the best of their era, and both played extremely significant roles in the most successful run in Astros history."
During his time with the Astros, Oswalt finished in the top five of the National League Cy Young Award voting in exactly half of his 10 seasons. He recorded back-to-back 20-win seasons in 2004-05 and finished 143-82 with a 3.24 ERA during his time with the Astros. He also helped guide Houston to the World Series in 2005, earning National League Championship Series MVP honors after going 2-0 with a 1.29 ERA in the six-game series victory over the Cardinals.
"To come back and retire as an Astro means a lot to me," Oswalt said. "I came up with the Astros organization and played on some great teams. Playing in the World Series in 2005 was the highlight of my big league career. I have a lot great memories from my years with the Astros."
As for Berkman, the six-time All-Star hit .296 with 326 home runs and 1,090 RBIs over his 12 seasons with the Astros. He led the National League in doubles in 2001 and again in '08, while also leading the NL in RBIs in '02, when he finished third in NL MVP voting.
"I'm really looking forward to this," Berkman said. "It's great to come back to Houston full circle. I've always considered myself an Astro and a Houstonian. I'm very proud to have played on some great Astros teams and proud to have played in what was probably the best era in franchise history. It is very appropriate to retire as an Astro."
In terms of all-time franchise ranks, Berkman ranks first in slugging percentage (.549), second in home runs, third in RBIs, walks and runs scored, and fourth in games played. Oswalt finishes his career as the Astros' all-time leader in win percentage (.636) and ranks second in both wins and strikeouts.
Paul Casella is a reporter for MLB.com. Follow him on Twitter @paul_casella. This story was not subject to the approval of Major League Baseball or its clubs.