Przybilla played for the Trail Blazers from 2004 until he was traded to Charlotte last February.
"We've been actively trying to get Joel to return to Portland for some time now and we're thrilled with his decision to come back to the Trail Blazers family," said acting general manager Chad Buchanan. "Joel is a hard worker, a great teammate and a player that does the little things to help you win, all qualities that will help us down the stretch run."
The 32-year-old has averaged 4.0 points and 6.3 rebounds in 553 career games with Milwaukee, Atlanta, Portland and Charlotte. Przybilla ranks fifth on the Trail Blazers' all-time list with 607 blocked shots.