Farirai Shereni, 25, attacked the woman as she made her way to work at about 4.30am on November 6 last year.
Shereni was using a phone charging point near McDonald’s in the Dale End area of the city centre, when he spotted the woman and asked for help.
Just moments later he launched a violent sexual attack, forcing her towards an underpass on Bull Street where he raped her.
When she managed to escape his grip, she ran to safety and rang her partner for help.
He called police who met the victim on Bull Street where she was able to provide a detailed description of her attacker.
Police flooded the area and picked up Shereni – who matched the description exactly – on CCTV. He was arrested less than 15 minutes later on Bull Street, at 4.45am on suspicion of rape.
Parts of the attack caught on CCTV were put to Shereni during interview. Although he admitted it was him in the footage he told police that he and the woman “got along" and “connected", and agreed to have sex with him under the bridge.
Despite professing his innocence, Shereni was charged with two counts of rape and one of sexual assault.
During a three day trial at Birmingham Crown Court, jurors were shown the footage - which cannot be released for identification reasons. It shows Mr Shereni grabbing and manhandling the woman.
This morning, the jury took just over two hours to deliver a guilty verdict on all charges.
Detective Constable Lyndsey Davenport, who investigated the case, said: “Shereni tried to discredit the victim’s account, but evidence uncovered as part of the investigation clearly shows that his account was completely untrue.
"The woman showed great courage in coming forward and without her bravery and support we may not have been able to bring him to justice.
"He now faces many years behind bars and I hope this will provide some sense of justice to his victim and her loved ones."
Shereni is due to be sentenced at Birmingham Crown Court on October 17.