The man, from Huddersfield, is to be questioned by police over Owen Wightman's death in Wakefield, West Yorkshire.
It comes after an appeal for anyone who had seen a male driver of a light blue or grey hatchback in the area at the time to come forward.
Owen and his friend had been playing just five minutes from their homes and were crossing the road when he was hit at around lunchtime on Saturday.
The driver of the car was seen stopping further down the road to inspect his car for damage.
Police have also analysed CCTV taken from a bus that passed the scene and have had a "good response" to appeals for help.
Older brother Jack, 12, has visited the road in the Chapelthorpe area and described Owen as the "best brother ever".
His handwritten note, left alongside masses of other tributes at the scene, said: "You was the best bro ever, even when we used to fight and argue I still loved you anyway."
On Monday, Owen's parents Joanne, 33, and Neil, 31, said they had lost their "baby" and appealed for someone to come forward so they could "lay him to rest".
In a statement they said: "He was a perfect little man who was taken from us - just perfect in every way. Read More