Henry will be part of the backroom staff alongside Graeme Jones, who was Martinez’s assistant at Swansea, Wigan and Everton.
Henry told social media: “Honoured to be assistant coach for Belgium. Thanks to Roberto Martinez and the Royal Belgian FA. Very excited. Can’t wait.”
Martinez said: “Thierry is an important figure. He will bring something different. He agreed right away to join us.”
The announcement was made as Martinez named his first senior squad since taking the Belgium job after Euro 2016.
Martinez was appointed at the start of August to succeed Marc Wilmots.
The appointment gives Henry the chance to impart his vast knowledge to some of the Premier League’s most potent frontmen – Romelu Lukaku, Christian Benteke, Divock Origi, Michy Batshuayi and Kevin De Bruyne.
It was also announced that fitness coach Richard Evans, who like Jones worked with Martinez at Swansea, Everton and Wigan, would take up a similar role with the national team.
