Hartenstein, 23, is 7-0 and averaged 7.5 points, 5.o rebounds, 3.5 assists and 1.8 blocks in four preseason games with LA.
He had been linked to the Clippers, Nets and Trail Blazers after finishing last season with the Cavaliers — then signed with the Clippers in early September.
Hartenstein declined his player option of about $1.8 million after playing the best basketball of his career with the Cavs, following a trade with the Nuggets in March.
In Cleveland, he averaged 8.3 points and 6.0 rebounds in 16 games, admirably relieving center Jarrett Allen when called upon. Hartenstein finished the season on the injured list.