Austin McGovern, from Dunbar in East Lothian, was last seen near the town’s Rowan Street at about 7.05pm on Friday September 9.
His family are now “very worried” and “just want to know he is safe and well”, Police Scotland said.
Officers were informed after Austin failed to return to his home in Summerfield Road on Friday evening, with Police Scotland adding that a number of “specialist resources” are now being used in the hunt for him.
Police are also carrying out door-to-door inquiries in the area, speaking to the youngster’s family and friends and reviewing local CCTV footage.
Meanwhile people living in the area are also being asked to check any sheds or outbuildings that he might have sought shelter in.
However, as it is “totally out of character” for him to go missing, Inspector Caroline Herbert spoke about his family’s concern.
She said: “A number of specialist resources are being used in our search for Austin, we are also liaising with partner agencies.
“Austin is only nine years old and it is totally out of character for him to go missing. His family is, understandably, very worried and just want to know he is safe and well.
“I am appealing to anyone who may have seen Austin or have any knowledge as to his whereabouts to contact us as a matter of urgency.”
Austin is around 4ft 4 in, and is described as being of stocky build with light brown hair. When last seen, he was wearing a red t-shirt and black trousers.