Boone fits the Astros' need for a utility infielder who has extensive experience at third. He has played in 950 career games at third, 102 at first, 30 at short and 23 at second.
He'll fill the role as a right-handed-hitting complement to Geoff Blum, who became the incumbent third baseman when the Astros non-tendered Ty Wigginton.
"Without Wigginton, we had to do something that would give us greater depth," general manager Ed Wade said. "We thought this combination was satisfactory."
Said Boone: "They're counting on me and Geoff to man [third base], and I feel like I'm ready to help us win."
Third-base prospect Chris Johnson will also have a chance to compete for a job during Spring Training next year, although it's more likely Johnson would start the season at Triple-A and serve as insurance in case of injury on the big league level.
"We think a pairing of Blum and Boone will be good for us," Wade said. "At the same time, we're going to be open-minded and give Chris every opportunity to make the club out of Spring Training."
Boone, who turns 36 on March 9, played in 104 games for the Washington Nationals in 2008. He hit .241 with six homers and 28 RBIs as a backup first baseman to Nick Johnson and Dmitri Young.
A veteran of 11 big league seasons, Boone began his career with the Reds in 1997. He spent seven seasons with Cincinnati until he was traded to the Yankees in the middle of the 2003 season.
He is probably best-known for his 11th-inning home run off Tim Wakefield in the 11th inning of Game 7 of the 2003 American League Championship Series, giving the Yankees a 6-5 walk-off win over the Red Sox -- and the AL pennant.
Boone injured himself in a pickup basketball game six weeks after the dramatic long ball and had surgery to repair the anterior cruciate ligament in his left knee. Because playing basketball was prohibited in his contract, the Yankees were able to void it.
Boone missed the entire 2004 season but returned with the Indians in '05, hitting .243 over 143 games. He spent two seasons with Cleveland before signing with the Marlins in '07 and Nationals in '08.
He had minor surgery at this time last year to clean out his left knee, and he's encouraged that he will enter Spring Training next year without any lingering health issues from the past.
"I feel like I'm in a much better place," Boone said. He also indicated Houston was geographically desirable, considering it's relatively close to Scottsdale, where he lives with his wife and son.
"It's easier for my family -- a little more reasonable for them to come and go," Boone said.
Boone comes from an accomplished baseball family. He is the son of former catcher and manager Bob Boone and the brother of former big leaguer Bret Boone. His grandfather Ray Boone played 13 seasons in the Majors as an infielder from 1948-60.