The statement from Macron's former boss -- Macron was economy minister when Valls was premier -- shows how the political map is being re-drawn in France in the wake of the 39-year-old's crushing victory over far-right candidate Marine Le Pen on Sunday.
"I will be candidate for the presidential majority and I wish to join the list (of candidates) of his movement," Valls, a Socialist, told RTL radio.
"Because I am a man of the left, because I remain a Socialist, I am not going to disown 30 years of my political life," Valls said. "I want Emmanuel Macron to succeed."
The new president has said he wants to break with the traditional left-right political axis in France and Valls is inextricably linked to unpopular outgoing Socialist President Francois Hollande.
Also Read
Valls resigned as prime minister to launch his own presidential bid but in a shock result was defeated in the Socialist Party's primary in January by left-wing candidate Benoit Hamon.
Hamon went on to make a disastrous showing in the presidential election, being eliminated in the first round in fifth place.
Macron's year-old movement -- it does not even have the status of a party yet -- has said it will field candidates in all 577 seats for the two-round parliamentary elections on June 11 and June 18.
But many analysts believe the centrist movement is unlikely to win a majority and will be forced to govern in a coalition.
Disclaimer: No Business Standard Journalist was involved in creation of this content