This was a winning proposal.

A Bronx woman running this year’s New York City Marathon dropped to one knee during the race on Sunday — to propose to her girlfriend.

Footage of the touching moment shows runner Clarisa Alayeto approaching the race’s 20-mile mark at 138th Street and Alexander Avenue in Mott Haven around 4:30 p.m., as family and friends cheer her on and her gal pal of one year, Mariely Del Valle, hugs her.

The couple’s favorite song, “Para Siempre” by Kany Garcia, can be heard playing and Alayeto suddenly kneels and pops the question — spurring tears from Del Valle, who also drops to the ground to embrace her.

“When I heard the song on the radio I thought ‘that’s weird’ and [then] I saw her on her knees and was just shocked,” Del Valle told The Post after the proposal.

The declaration of love was definitely a “surprise” for Del Valle.

Last night I asked her ‘you’re not going to propose tomorrow are you?’ And she said ‘of course not that’s too much for me.’”

Little did she know, Alayeto had been planning the moment for weeks.

The couple, both 37, have known each other “for forever” but connected on Facebook a year ago, said Del Valle, a teacher at DREAM Charter School.

It was Alayeto’s first time running the marathon, and she decided to stick with the endeavor, even after her grandmother’s passing two months ago.

“She just lost her grandmother and so this was big for her,” said Raquel, a friend of Ayaleto’s who came out from Far Rockaway to cheer her pal on and witness the proposal.

“I think it was monumental for her so why not make the person who is monumental to you?,” said Raquel, who didn’t give her last name.

Family members, including siblings, cousins, nieces and nephews and aunts and uncles of the women were also there to commemorate both occasions.

After popping the question, Ayaleto, a government worker, continued running, completing the marathon in just under nine hours.

“I can’t wait to marry my best friend!,” Del Valle gushed.