Chris Vigo took to one knee in the middle of the structure with his long-term partner Angelina Rivera to ask if she would marry him on Tuesday.
The event was meticulously planned and Mr Vigo even asked a friend to photograph the moment.
However as his pal lent in to get a better shot, he stood in a bike lane and collided with a cyclist who nearly careered into the couple.
Although the photos may not have come out the way Mr Vigo intended, he managed to record the proposal from a stationary camera and uploaded it to social media.
The footage opens with him kneeling in front of his 21-year-old girlfriend.
His friend is then seen in shot, snapping away in the bike lane.
An approaching cyclist shouts at friend Josh Rosario to get out of the way.
After avoiding that collision Mr Rosario steps back into the lane to resume his photographic duties.
However this time he is wiped out the way by another rider, who almost faceplants the couple.
Speaking to the New York Post, Mr Vigo said his friend was "so excited" to document the moment, that he wasn't aware of the hazard.
He added: “In my mind, I’m like, ‘do I go over and help him, or do I stay and hold her hand?’ ”
Mr Rosario said he was unhurt in the incident and added: "I’ve lived in New York my whole life, I had never been to the Brooklyn Bridge.
"I didn’t know there was a special bike lane".
It wasn't all bad news however and the couple are now engaged to each other.
