Johnson, 31, will sign his second consecutive one-year deal with Philadelphia, where he averaged 4.6 points and 4.5 rebounds a game last season.
Sixers coach Brett Brown -- now the interim president of basketball operations -- considers Johnson an important culture builder with his young core.
The Sixers are signing back two important leadership pieces, Johnson and guard JJ Redick, on one-year deals.
Johnson has played 13 NBA seasons and remains the last NBA player to be drafted straight out of high school. He has averaged 7.2 and 5.5 rebounds during stays with Detroit, Toronto, Boston and Philadelphia.
Johnson has appeared in 50 playoff games in his career, starting 25.