The 35-year-old was taken into custody following the alleged incident involving a woman the night before his team's FA Cup fixture against Sutton United. He was later released on bail.
A Metropolitan Police spokesman: "Police were called at approximately 11.10pm on Saturday December 3 to a hotel in Purley Way, Croydon, following an allegation of sexual assault.
"A man, aged 35, was arrested on suspicion of sexual assault and taken into custody at a south London police station.
"He was subsequently bailed to a date in late January pending further investigation by officers from Croydon borough."
The club said in a statement: "Notts County can confirm that the club are aware of an alleged incident involving one of our players at the team's hotel on Saturday, December 3.
"As this is a police matter, the club will be making no further comment on this incident."