The 31-year-old has signed a one-year-deal at Portman Road and could make his debut against Crewe on Tuesday.
Scotland said: "I am delighted to have joined Ipswich and look forward to trying to help the club get into the Premier League."
The striker began his career in British football at Dundee United, taking in two years at Tannadice before joining St Johnstone in 2005.
He then moved to Swansea City in 2007 and enjoyed a great spell with the Welsh outfit, notching over 50 times in all competitions.
His fine form soon drew Premier League interest and he followed former Swans boss Roberto Martinez to Wigan in 2009.
He struggled to make an impact at the DW Stadium, though, and will be hoping to get his career back on track at Ipswich.
Source: Team Talk
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Source: Team Talk