Martin reached a deal worth $32 million according to ESPN, which said the Sixers will also release frontliner Paul Reed.
Martin, a 28-year-old American, figures to replace Tobias Harris, who reached a two-year free agent deal with Detroit, in a starting lineup set to include past NBA Most Valuable Player Joel Embiid, star guard Tyrese Maxey and Paul George, the former Los Angeles Clippers forward who reached a four-year deal worth $212 million with the 76ers.
All deals remain unofficial because of an NBA signing moratorium, leaving it to media reports to track the NBA free agency talent reshuffle.
The Sixers have also signed free agent guard Eric Gordon and center Andre Drummond as they work to revamp the roster and build a contender to challenge the reigning NBA champion Boston Celtics.
The 76ers have not reached the Eastern Conference finals since 2001.
Martin, who played two seasons in Charlotte before joining the Heat in 2021, averaged career highs of 10.0 points and 2.2 assists plus 4.4 rebounds a game last season for Miami.
Malik Beasley, an eight-season NBA guard who played in Milwaukee last season, has signed a one-year deal worth $6 million with the Detroit Pistons, according to multiple reports. He averaged 11.3 points and 3.7 rebounds a game last season for the Bucks.
