River, who famously starred in the 1986 coming of age film Stand By Me, died from a drug overdose outside the Viper Room club in Hollywood in 1993, when he was 23-years-old.
While is a notoriously private person, he has now opened up about the tragic death in a special episode of 60 Minutes with US journalist Anderson Cooper.
“I feel like in virtually every movie that I made, there was a connection to River in some way,’ Joaquin said.
“And I think that we’ve all felt his presence and guidance in our lives in numerous ways," he said referring to his family, who partially featured in the interview.
Joaquin added that he and his family were unaware of River's fame at the time of his death as they “were so removed from the entertainment world,” not consuming television shows or magazines.
“River was a really substantial actor and movie star, and we didn't really know it,” the Oscar nominee said.
“So during that time in which you're most vulnerable, there are helicopters flying over. There are people that are trying to sneak onto your land.
“Certainly, for me, it felt like it impeded on the mourning process, right?”
The actor’s mother, Heart, agreed, adding that she still gets hit by moments of grief having not dealt with the loss of her son properly at the time.
“The grieving process happens out of nowhere, you know?” she said.
“I'll be driving and all of a sudden, I will feel it. And I'll just welcome it."
Joaquin recently became the latest celebrity to be arrested as part of Jane Fonda's weekly climate change protests.
“Something I think isn’t oftentimes talked about in the environmental movement or in the conversation about climate change is that the meat and dairy industry is the third leading cause of climate change,” he said.
“I think sometimes we wonder what we can do in this fight against climate change and there’s something that you can do today, right now, and tomorrow, by making a choice about what you consume.”