All-rounder Faulkner, who turned 29 on Monday, shared a picture of himself at a restaurant with his mother and a male friend with his 339,000 followers on Instagram and wrote: "Birthday dinner with the boyfriend".
He added the hashtag "#togetherfor5years".
The post drew over 20,000 "likes" and supportive comments from fellow international cricketers.
Australia all-rounder Glenn Maxwell wrote: "Happy birthday mate! Great courage."
Former Australia fast bowler Shaun Tait echoed the sentiment, posting: "Great courage mate, bet you feel better happy birthday."
Global media, including Britain's Daily Mail and The Guardian, reported that Faulkner had become the first Australian cricketer to "come out".
Cricket Australia (CA) poured cold water on the reports, however, with a spokesperson saying Faulkner had made a "joke" that was "taken out of context".
Both CA and Faulkner later issued statements clarifying that the "boyfriend" was actually a long-time house mate and good friend of the cricketer.
"There seems to be a misunderstanding about my post from last night, I am not gay, however it has been fantastic to see the support from and for the LBGT community," Faulkner wrote in a follow-up post on Instagram.
"Let's never forget love is love, however @robjubbsta is just a great friend. Last night marked five years of being house mates! Good on everyone for being so supportive."
CA apologised on Faulkner's behalf for any "unintended offence" while taking a shot at the media that reported he had come out.
"His comment was made as a genuine reflection of his relationship with his business partner, best friend and house mate of five years," CA spokeswoman Karina Keisler said.
"He was not contacted for clarification before some outlets reported his Instagram post as an announcement of a homosexual relationship.
"James and CA are supportive of the LGBQTI community and recognises coming out can be an incredibly emotional time.
"The post was not in any way meant to make light of this and, though the support from the community was overwhelming and positive."
Faulkner was named man of the match at the World Cup final in Melbourne four years ago but has not played an international since a one-day game away to India in Oct. 2017.
(Reporting by Ian Ransom; Editing by Greg Stutchbury)
