A dedicated dad of two was knocked to the ground and killed when a bicyclist rammed into him during his morning walk to work in Central Park last week, his family and police said.

Richie O’Brien, 41, strolled through the iconic green space on the way to his steamfitter job during the dawn hours of Sept. 23, when the cyclist pedaling north on the park’s East Drive near East 84th Street struck him, according to the NYPD and a fundraiser launched by his loved ones.

The impact threw O’Brien to the ground and caused severe head trauma, for which medics rushed him to Weill Cornell Medical Center. He succumbed to his injuries on Sunday, his family said.

“Although our hearts are broken by this unimaginable loss, Richie’s legacy will live on,” his family posted on a GoFundMe page.

Kin described O’Brien as “a proud Local 638 Steamfitter who went to work every day to provide for his family and give his wife, Ronni, and their two daughters, Kylie and Mia, the life they deserve.”

Kylie and Mia are 12 and 8 years old, respectively. 

O’Brien set out for work one last time as cyclists, runners and walkers criss-crossed the still-dim park around 6:30 a.m., family and police said.

Witness Laura Sackler said the sound of a nearby collision reached her ears as she finished her morning run just behind the Metropolitan Museum of Art.

“I heard the impact and turned around, and tragically, Richie and the cyclist were both on the ground,” she told The Post on Monday.

“Richie unfortunately was unconscious from that moment forward and never gained consciousness. He was bleeding,” she said.

The cyclist sat up, visibly shaken and confused, and stayed at the scene as a crowd of good Samaritans – including a doctor — gathered around to help O’Brien, Sackler recalled.

“He was just in disbelief because he had been part of something. He was like, ‘I can’t believe this,’” Sackler said. “That was about it. He just sat there in silence most of the time.”

Bystanders and pedestrians formed a circle around the bleeding and unconscious O’Brien, but their act of kindness wasn’t appreciated by some on-the-move passersby.

“There were some aggressive cyclists going by during this tragic moment who were yelling at us to move out of the way because we were in their way causing problems,” Sackler said.

“One of the issues is that the culture of the cyclists in there, they’re really using it like a trackway. They’re really using it like an area where they’re able to get their training and speed work in around the park,” she said. “I’m an athlete, and I’m a runner, and I have many friends who are cyclists, and I’m a huge advocate for all of us being able to use Central Park — but there’s serious issues with speed.”

An ambulance arrived after roughly 20 minutes, Sackler said, declining to into more detail out of respect for O’Brien’s family.

The cyclist, 32, was treated at the scene and declined an ambulance, according to police, who did not identify him or say whether he would face any charges.

The NYPD’s Collision Investigation Squad was reviewing the case.

Brian Hunt, the president of the steamfitters’ union, said O’Brien was working on a project at the nearby Metropolitan Museum of Art and described him as “a good influence to those around him.”

“Like many of us here in New York City, Richie woke up early every morning and came to work to help keep the New York City economy moving by building the projects that we build every day here,” Hunt told The Post on Monday. 

“He was an example of what a good steamfitter is supposed to be, and for anybody working blue collar in the city, or anybody working white collar and anybody working in Manhattan.”

Hunt said “everybody is still just reeling from the loss of Richie.”

“I don’t know what’s going to happen moving forward,” he said. “Manhattan is a difficult place for commuters. Everybody has to pay attention, whether you’re on a vehicle that has wheels, or if you’re a pedestrian, everybody has to pay attention because it’s Manhattan.”

O’Brien died early Sunday with his wife Ronni by his side, according to the family fundraiser.

His brother-in-law Jason Bullara, writing in a heartfelt Reddit post, thanked the strangers in Central Park who stayed by during “one of the worst moment’s of Rich’s life.” 

O’Brien donated three of his organs before his death, Bullara revealed.

“Even at the end of his life, he was able to give other people a chance at theirs,” he wrote. “He was, quite simply, the best person I knew.

“And somehow, even in death, he was still giving to other people.”