Fabregas leaves Stamford Bridge after a four-and-a-half-year spell that saw him play a key role in two Premier League title triumphs and win the FA Cup and the League Cup.
Chelsea's pursuit of a replacement has not been fully funded be Fabregas' departure, but we could receive up to £10M depending on his and Monaco's performances over the next three-and-a-half-years of his contract.
Now 31, Fabregas eventually made the same move as Henry when he left the Emirates Stadium for Barcelona, but he returned to English football with Chelsea in 2014.
"Big goals and outstanding moments of quality, all backed up by the ultimate aim, which is to be part of a successful, trophy-winning team".
And on the £10m switch, new No.44 Fabregas told Monaco's official website: "It is a great pleasure to join AS Monaco, a new project for me".
Former France and Arsenal striker Henry took charge of Monaco, where he started his playing career, in October - but they have only won twice under his stewardship and are one place off the bottom of Ligue 1 on 13 points from 18 games.
Fabregas scored 22 goals for the London club in 198 appearances.
"I'm here to help the team, I'm looking forward to starting, we have a great match to play in Marseille on Sunday. I am very excited".
'Michy? I know him, we rubbed shoulders with Belgium, he is a player who can be interesting, ' Henry said.