Harrell's deal is fully guaranteed, sources said.
Harrell, 24, joined the Clippers as part of the Chris Paul trade with the Houston Rockets last season and made an imprint with his rebounding and defense. Harrell averaged 11 points and 4 rebounds in 17 minutes per game for the Clippers.
For his agent, Rosenhaus, the deal represented his first NBA free-agent deal after decades as one of the NFL's most prominent dealmakers. Rosenhaus Sports has moved into basketball and also represents Portland Trail Blazers first-round pick Anfernee Simons.