A manhunt was launched after the young girl was approached at around 4pm on September 30 last year, by a man who suggested he had a knife before grabbing her by the wrist and leading her to the park.
He then sexually assaulted her before leaving the area.
Police launched an investigation, which involved reviewing CCTV from around the crime scene.
They found an image of the suspect, which was then distributed publicly through a media appeal.
As a result of the appeal, police received two calls from members of the public who identified the man in the image as 38-year-old Samuel Cortez.
Cortez, from North Finchley, was arrested on December 15 last year, taken into police custody and subsequently charged.
At Harrow Crown Court on Thursday, Cortez was jailed for nine years after pleading guilty to sexual assault of a child under the age of 13.
He was also sentenced to three years and nine months’ imprisonment for child abduction - a sentence that will run concurrently.
During the sentencing, the judge ordered that Cortez will be on licence for five years after completing of his sentence. He will also be on the sex offenders register for life.
Detective Constable Chris Finnegan of the North West Command Unit, who led the investigation, thanked the young victim for her “immense courage” during the investigation.
“This was a terrifying ordeal for the young girl but she, with the support of her family, has shown immense courage and strength in supporting our investigation,” he said. “I hope it offers some reassurance that the man responsible is now behind bars.
“Identifying Cortez was a combination of diligent police work along with the support of the public. This is a great example of how policing should work and it has resulted in a vile individual being taken off the streets.”