"I have resigned as minister for Transport and Roads for personal reasons, not for any reasons relating to my ministerial duties," he said.
"I apologise to my wife, family, colleagues, staff and the community for letting them down. This will be a very difficult time for my family and friends and I ask for their privacy to be respected."
A short time later, Channel Seven aired footage of Mr Campbell allegedly visiting the club at Kensington, in Sydney's eastern suburbs.
Mr Campbell said he would remain in parliament as the member for Keira.
"I am incredibly proud of my achievements while serving as minister for Transport, Roads, Police, Small Business, the Illawarra, Regional Development and Water Utilities," he said.
Mr Campbell has been under pressure to resign on numerous occasions this year, most recently for his handling of accident on the F3 north of Sydney which left motorists stranded for hours.
The opposition has also called for him to stand down over the tens of millions lost on the scrapped CBD Metro.
