The 23-year-old right-back, who played for England against Moldova in Friday's World Cup qualifier, allegedly sucked in the potentially deadly nitrous oxide several times during a night out in Sheffield last June, the Sunday Mirror reported.
The controversial laughing gas, which is portioned into balloons and sold for as little as $3, is a legal but dangerous high and has effects likened to those of crack cocaine or heroin after taking a huff.
It has been known to cause users suffocation, seizures, strokes, blackouts, chronic depression and strain on the heart. The drug is not as prevalent in US clubs as it is across the pond.
The Sunday Mirror said that Walker, who plays for Tottenham, allegedly inhaled a number of times from the balloon while out with friends on June 1. He was recovering from an injury that forced him to sit out England's friendly double-header with the Republic of Ireland and Brazil.
Walker, the Player of the Year last season, is expected to line-up against for England in Ukraine on Tuesday in a must-win World Cup qualifier.
"More and more canisters of laughing gas started appearing," said an eyewitness at the club.
"Kyle and his pals were getting well carried away with them. He didn't mind one bit that people were taking pictures."
"Hippy crack" first became popular during the 1960s, but has now become a popular legal high in British nightclubs, where it is sold for a few bucks.
The FA have declined to comment.