The reward, donated by independent charity Crimestoppers, was announced on BBC’s Crimewatch Live on Tuesday.
The incident occurred in the early hours of Friday, July 4, when the victim, a woman in her early 20s, was approached by a man in the Essex Road area of Islington.
At around 3.20am, he began walking alongside her and harassed her before dragging her into the entrance of a building on Church Road, where he assaulted and attempted to rape her.
Two members of the public heard the woman shouting for help intervened, with the suspect was last seen fleeing towards Angel.
Met detectives have now released an image of a man they would like to speak to in connection with their investigation, along with the announcement of the reward.
Police would like to speak to this man in connection with the attack
Met Police
The man is described as being of average build and approximately 5ft 8ins to 6ft tall, with short hair or a shaved head at the time of the attack.
He was wearing a distinctive tie-dye T-shirt featuring blue and pink streaks.
Police have spoken to one of the witnesses, and are keen to speak to the other.
The witness, who restrained the attacker for a short time before he made off, is described as a white man in his late teens or early 20s, with an athletic build and curly ash-blonde hair.
Detective Chief Inspector Paul Ridley, who announced the reward, said “The victim continues to be supported by specialist officers, but this attack has understandably had a devastating impact on her day-to-day life.
“We’ve conducted extensive enquiries using a range of investigative tools, but we need to trace this man, and we believe the public can help us do that. If you recognise him, please contact Crimestoppers. The information you provide could help bring a victim justice and you could receive a reward of up to £10,000.
“Even if you are not completely certain, please make that call and let us carry out the necessary enquiries.”
Alexa Loukas, London Regional Manager at Crimestoppers, said: "This was a violent and distressing attack that has had a significant impact on the victim, and our thoughts remain with her.
"Through this reward we hope to encourage anyone who knows who this man is, or who has information that could help identify him, to come forward. Even information that may seem insignificant could be the missing piece that detectives need.
"We understand that some people may feel uncomfortable speaking directly to the police. As an independent charity, Crimestoppers gives people another option. Anyone contacting us can pass on information completely anonymously. We do not ask for personal details, and no one will know you contacted us.”
Anyone with information has been urged to contact police via 101 quoting CAD 1303/4JUL26, or to contact Crimestoppers by calling 0800 555 111 or through their website.