Maelys de Araujo, aged nine, vanished from the venue, a community hall in the village of Pont-de-Beauvoisin near Genoble, on August 27.
Despite a painstaking search by police using sniffer dogs, the child has still not been found.
According to prosecutors, the dogs lost the scent from Maelys’ cuddly toy in the car park, leading to suspicion she had been driven away.
The arrested man, a guest at the wedding, was initially interviewed and released, police said.
But he was later recalled when fresh evidence came to light.
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A lawyer for the man, who has not been named, claimed the youngster had got into his client’s car but he denied abducting her.
The lawyer, Bernard Meraud, said: “He declared that the little girl got into the vehicle with a little boy, on the back seat, to see if (the suspect’s) dog was in the boot.”
DNA of the missing girl was found on his car dashboard, the lawyer said.
Prosecutors say the man has been charged with kidnapping, illegal confinement or arbitrary detention of a minor of less than 15 years.
His car had come to the attention of investigators when he washed it after the wedding, with the intention of selling it.
Prosecutors said he had persistently denied being involved but “this did not convince the investigative judges, who decided to hold him”.
Divers and carers have all scoured the area for Maelys in recent days but have so far been unable to trace her.
Police chief Yves Marzin said: “It is like looking for a needle in a haystack, extremely tedious work but very important.”
So far around 250 people have been interviewed by investigators, including most of the wedding guests.
One wedding guest, told Le Parisien: “The DJ for the evening announced on the microphone that a child had disappeared. Suddenly, everyone started searching, in the main hall and outside.
“It was anguish. To see the disappearance of a nine-year-old, that’s not nothing.”