Legendary forward returns to north London following a protracted move and will now look to extend his record goal tally in a maximum of 10 games for the Gunners over winter
The move has been in the works for weeks but had been held up due to negotiations between the Gunners and Henry's current club, the New York Red Bulls.
Henry could feature in eight Premier League games if fully fit and available, the last of which could be a mouth-watering north London derby against Tottenham.
A statement from Arsenal read: "Thierry Henry has today rejoined Arsenal on a short-term loan deal.
"After negotiations between Arsenal, Henry, the New York Red Bulls and Major League Soccer, the striker will team up with the Gunners on a temporary basis during a period of fixtures in January and February that will see Gervinho and Marouane Chamakh depart for Africa Cup of Nations duty."
A bronze statue of Henry was recently unveiled at the Emirates Stadium alongside iconic former skipper Tony Adams and revolutionary manager Herbert Chapman, and the Frenchman admitted his surprise at the deal.
"It is unreal to be honest," Henry told Arsenal's official website. "But when it comes to Arsenal my heart will always do the talking. Once I knew the plan behind it I was okay with it. I am not coming here to be a hero or prove anything, I am just coming here to help. People have to understand that.
"Marouane and Gervinho are going to the Africa Cup of Nations, so I was asked to fill in the gap. It is a loan deal and I’ll be on the bench most of the time. If I can make the bench that is! The boss has a team here already who are doing something good. I am just going to be part of the squad."
Henry also moved to reassure New York Red Bulls supporters, some of which were reportedly concerned that their star striker may not return to the club.
"I want to send a message to the fans of New York Red Bulls as well," Henry told the site. "I always said I would not play in Europe again. But it is hard for me when it comes to Arsenal.
"I am not coming here for the whole season, I will be back and I want to win the MLS Cup with the Red Bulls. I hope it is win-win situation where I can help Arsenal and come back fit for the MLS season."
Henry is Arsenal's record goalscorer after netting 226 times in 369 appearances after joining from Juventus in 1999.
Originally a winger, Henry was transformed under Arsene Wenger into one of the world's most feared strikers, winning Premier League and FA Cup titles.
“I am very happy," the manager said of the signing. "It was my desire and Thierry’s desire. We will have Thierry for January and in February and then he will go back to the United States.
"I am sure during these two months he will be a massive asset to the team in the dressing room and on the pitch. He can be relaxed, not under too much pressure and be a tremendous help to the team.”
Henry had a stint as Gunners captain before going on to Barcelona where he won every competition possible in one magnificent year under Pep Guardiola in 2009.
The Frenchman has also won the World Cup and European Championship with his country, for which he is also the record goalscorer with 51 strikes in 123 international games.