Cooper completes Pompey return
The 29-year-old utility man spent the second half of last season at Fratton Park, scoring twice in 14 appearances for the Blues.
Cooper, who came through the youth ranks at Pompey before moving to Bournemouth in 2005, was a free agent again this summer and appeared to have missed his chance to rejoin when Guy Whittingham turned his attentions elsewhere.
But despite interest from other clubs, Cooper has now returned to Pompey and goes straight into the squad that travels to Cheltenham this weekend.