Henry, 34, who is currently playing for the New York Bulls, made 370 appearances for Arsenal from 1999-2007 and remains the club's leading goal-scorer with 226 goals.
"Thierry Henry has today rejoined Arsenal on a short-term loan deal," the north London club said in a statement on their website.
"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."
Henry, who has been training with the club, told the website that manager Arsene Wenger had asked him to help during the absence of the two players.
"When it comes to Arsenal my heart will always do the talking," he said.
"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 reassured Red Bulls' fans he planned to return.
"I am not coming here for the whole season, I will be back and I want to win the Major League Soccer 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, who played for Barcelona after leaving Arsenal, was a member of the France team who won the 1998 World Cup and 2000 European Championships.
A bronze statue of Henry was recently unveiled at Emirates Stadium alongside former captain Tony Adams and Herbert Chapman, their innovative manager in the late 1920s and early 1930s.
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