On Thursday morning, the Latics confirmed they had completed the deal to bring Scharner back to the club he spent more than four years with before leaving in the summer of 2010.
The Austrian, who can play in midfield but is set to be utilised by Wigan boss Roberto Martinez as a central defender, told Latics Player: "It feels as though I've come home. My first spell here lasted four-and-a-half years with many happy memories, so I'm delighted to get this opportunity to return.
"When I discovered that the manager wanted to bring me back, there was no question about it, it was an easy decision. I haven't been playing much in Germany with Hamburg and for me there is no better place in England to come to than Wigan.
"Since leaving I've had a few ups, and probably more downs to be honest but I'm still looking after myself fitness-wise and feel ready to give 100% to help us stay in the Premier League, my new challenge."
Wigan, currently 18th in the top flight, as well as being through to the fifth round of the FA Cup, have lost one centre-back in Ivan Ramis for the rest of the campaign due to a knee injury while another, Antolin Alcaraz, is yet to return to action from a groin problem.
Martinez has been keen to strengthen in the position and will now be able to select Scharner for Saturday's home league clash with Southampton.
The 32-year-old, a fans favourite during his first spell with the Latics, had the word 'THANX' dyed into his hair when he made his last appearance at the DW Stadium for the club and he is looking forward to greeting the Wigan supporters again.
"We've got a very important game this weekend against Southampton, and of course it's my first game back at the club which I'm going to work hard to be ready for," Scharner said. "I'm looking forward to seeing the fans again and, if given the chance, I'll do my best on the pitch to try and get the win.
"I'm here to help the team and to help the club survive in the league, and with 14 games remaining I'm confident that we can do that. The last time I wore a Wigan Athletic shirt (at home) I put the word 'THANX' on the back of my head so I'm thinking maybe something like 'I'M BACK!' this time around!"