The veteran forward joined the Wizards at Wednesday's practice and will be available for Thursday's game against the Toronto Raptors.
Gooden agreed to the deal Tuesday. The Wizards were in need of frontcourt depth after losing forward Nene to a sprained left MCL.
Nene is expected to be sidelined about six weeks.
Gooden hasn't played since he was designated as an amnesty player by the Milwaukee Bucks last summer. He had two years and about $13.4 million remaining on his contact at the time.
The 32-year-old Gooden has played for nine teams over 11 NBA seasons.
The Wizards also assigned rookie guard Glen Rice to the Iowa Energy of the NBA Development League for the second time this season.
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