The Football Association said Walker’s use of nitrous oxide – also known as laughing gas – did not contravene England’s player code of conduct.
Walker, who is set to play in tonight’s match against Ukraine, has apologized, saying: “Now I know the health risks, it was poor judgement on my part.”
The FA recognised the right-back’s contrition and said he had discussed the matter with manager Roy Hodgson.
“Kyle has accepted his mistake,” said an FA statement. “He has assured us it won’t happen again.”