The 39-year-old will sign a one-year deal for the veteran's minimum, according to The Associated Press' Tim Reynolds.
Haslem has spent his entire career with his hometown team after signing with Miami as an undrafted free agent in 2003. He was the starting power forward for several seasons before taking a step back to become the respected voice in the locker room.
"We are proud to welcome our captain back for a 17th season," Heat president Pat Riley said, according to the Sun Sentinel's Ira Winderman. "UD is the heart and soul of Miami and we are proud to have him help lead this team once again."
Haslem is among the most valued athletes in the city's history, playing a crucial role in each of the Heat's three championship runs. The veteran big man averaged just 2.5 points and 2.7 rebounds across 10 contests last season.