Marshall, an 11-year-veteran who played for the Toronto Raptors last season, was courted by a handful of teams before reaching an agreement with the Cavaliers, said his agent, Andy Miller.
"We look at this as an opportunity to join a team that could
win an NBA championship real soon," Miller said.
Miller would not disclose financial parameters of the deal.
Marshall is the third significant player signed by the Cavs this summer and probably not the last. The club, which was $28 million under the salary cap, is expected to officially re-sign All-Star center Zydrunas Ilgauskas and sign guard Larry Hughes on Friday when the free agent signing period begins.
Coming off the bench last season, the 32-year-old Marshall averaged 11.5 points, 6.5 rebounds and shot a career-best 42 percent on 3-pointers for the Raptors. The Cavs are desperate for outside shooting to offset teams collapsing on Ilgauskas or double- and triple-teaming James.
Marshall has averaged 12.4 points and 7.3 rebounds over his 11-year career, and despite being 6-foot-9, he has made 35 percent of his 3-pointers.
In 2003-04, Marshall was the only player in the NBA to rank in the top 25 in rebounds (9.9), blocks (1.5) and 3-point percentage (.403).
A star at Connecticut, Marshall was selected with the No. 4 overall pick in 1994 by Minnesota, which traded him after one
season to Golden State for Tom Gugliotta.
He played six seasons with the Warriors before being traded to Utah. Marshall also played for Chicago.