Judge Lord Bannatyne told 28-year-old Stuart Hatch: "These events have had an appalling effect on your rape victim."
Lord Bannatyne also described sexual remarks made by Hatch to a group of teenage girls at the party as "nasty".
The High Court in Glasgow heard the attack took place at a house in Paisley, Renfrewshire, where the celebration was held in September last year.
Hatch – whose pregnant wife was also at the party – had earlier been heard making lewd comments to other girls.
Prosecutor Shirley McKenna said Hatch was heard directing "sexual remarks" towards young female guests, which left them feeling "uncomfortable".
One described Hatch as "getting creepier and creepier".
Some of the girls decided to leave due to his behaviour.
The victim was later in a bedroom at the house where the attack took place.
Miss McKenna told the court: "She was scared, but pretended to be asleep."
The girl fled the house after the attack and went to a friend's home where she was found to be "crying hysterically".
She said she had been raped and the police were contacted. Hatch was later detained and claimed at the time that he had been "cuddling" with the girl.
Hatch pleaded guilty to raping one girl and to a separate charge of making sexual comments to young girls at the party.
Defence counsel Louise Arrol said: "The only thing he could do to demonstrate his remorse was by admitting his guilt.
"He is aware of the impact the offence has had on this girl and will continue to have.
"He had been in full-time employment and ultimately became a manager, but this caused him stress and he was consuming more alcohol."