The 6-foot-10 Foyle was available after he and the Golden State Warriors agreed on a buyout earlier this month.
"Adonal [Foyle] is a solid shot blocker and post defender," Magic general manager Otis Smith said. "His presence helps fortify our frontcourt, while bringing us veteran leadership."
Foyle signed a six-year deal worth nearly $42 million in July 2004 and had spent his entire career with Golden State. But he rarely played last season in coach Don Nelson's guard-oriented lineups.
The 10-year veteran has appeared in 641 regular season games,
averaging 4.4 points and five rebounds per game. He has a career average of 1.78 blocks per game and was the Warriors' all-time leader in rejections with 1,140.