The 37-year-old striker from Esher has already pleaded guilty to possessing cocaine at Guildford Crown Court.
He faced charges after an incident in which he was reportedly Tasered by police responding to reports of a break-in at his home in Claremont Lane.
Judge Stephen Climie told him a custodial sentence would be justified.
Adjourning sentencing until 12 February, the judge told Bent: "I expect the Probation Service to prepare a report on you which you are required to attend for interview to discuss in greater detail the background to what on paper is a disturbing set of events, which I'm sure you appreciate.
"On the face of it a custodial sentence is justified.
"Whether that is the right sentence in the context of this case is not a matter I will prejudge."
Bent had denied two other charges of possessing bladed articles, namely a meat cleaver and a kitchen knife, which will be left on file.
He had previously denied affray but changed his plea on Wednesday.
The ex-England Under-21 international played 574 games and scored 113 goals during his professional career.
He played for 14 different clubs including Wigan Athletic, Charlton Athletic, Everton and Leicester City.
Bent also played as a striker for Sheffield United, Blackburn Rovers, Ipswich Town and Birmingham City.
He was released on unconditional bail.
Ex-Premier League footballer Marcus Bent has admitted a charge of affray after an incident at his home in Surrey last September.