The 20-year-old scored one goal in six appearances for Dave Jones' side last season.
Wickham will remain at Hillsborough until 1 January and is in line to make his second debut for the Championship side against Reading this weekend.
The England U21 international joined Sunderland from Ipswich in June 2011 and has played 40 times for the club.
"I'm really pleased to come back to Sheffield Wednesday," Wickham told the club's official website.
"There was interest from other clubs but I feel I have unfinished business here and I can't wait to get started again.
"I know the manager, I know the players and the place and that was a big influence in my decision."