The 25-year-old on Tuesday signed a new four-year contract extension with the Cottagers and immediately moved to Portman Road on a season-long deal.
Fulham are believed to have inserted a recall clause into the deal should first-choice keeper Mark Schwarzer suffer an injury.
Stockdale has made 13 appearances for the Londoners since arriving from Darlington in 2008 and has had loan spells at Leicester, Plymouth and Rotherham.
"I had a great talk with the gaffer here and Ipswich Town is a big club so I was eager to come here," Stockdale told the club's official website.
"The manager told me about the quality of the signings he's made and where they're heading and everything he told me made me keen to join the club. Now I'm just looking forward to getting going and playing my part in what I hope will be a successful season for Ipswich."
Source: PA
Source: PA