EXCLUSIVE: Alan Thicke's Son Carter Credits Leonardo DiCaprio for Helping Him Get Through Dad's Tragic Death

The 19-year-old son of the late 'Growing Pains' actor tells ET his dad's co-star is 'just the most amazing guy.'

Carter Thicke is getting candid about the tremendous support he's received following the tragic death of his father, Alan Thicke.

In an exclusive sit-down interview with ET special correspondent Keltie Knight, the 19-year-old praised one actor in particular for helping him get through it all: His dad's Growing Pains co-star, Leonardo DiCaprio.

WATCH: Alan Thicke Remembered at Star-Studded Memorial Hosted by Son Robin

During Alan's star-studded memorial service held at his ranch in Carpinteria, California, last month, DiCaprio gave a moving speech in honor of his close pal, who died at age 69 after suffering a heart attack while playing hockey with Carter.

"You could see [Leo's] genuine love and respect for my dad," Carter said of the Oscar winner and environmental activist. "Leo is just the most amazing guy. I mean, when it's the environment and then this, he is the most incredible, down-to-earth, just loving guy."

"And, you know, [he's] also the busiest guy on earth," Carter continued. "To take his time to come out and share his respects and spend time with the family -- he was really, really incredible through all of this."

Carter actually credited the entire Growing Pains cast for being there throughout this tumultuous time, telling ET, "They're an amazing group and they've been around a lot."

"We did the -- I think they did the Growing Pains anniversary special at the ranch recently, so I've kind of grown up with all of them and their children," he added. "So, it was really, really incredible to have them there."

WATCH: Alan Thicke's Son Carter Opens Up About Their Heartbreaking Last Moments Together

He was also grateful to see some of Alan's best friends at the service, like Bob Saget, Bill Maher, Wayne Gretzky and David Foster. "These guys that I've grown up with … just opening their hearts out and crying and telling these hilarious stories," he said. "It was incredible to see, because he really did touch so many people's hearts."

"David Foster was incredible at the funeral," Carter noted. "He told one of the funniest and most beautiful and touching stories as his eulogy at the funeral. There was just so many people who just cared and it was so genuine and just a lot of love for him."

Later in our interview, Carter also opened up about the outpouring of love he and his family received from fans on social media. From personal messages to beautiful tributes, Carter said it was "enlightening" to see how many hearts his father touched over the years.

"It was just random people on the internet, you know. It was amazing to see the outpour for him and it was -- that was something that made me really, really, really proud," he explained. "That was at least a shining moment 'cause I knew that [my dad] would be ecstatic to be the No. 1 trending topic on Twitter. I'm sure he would have loved that."

But out of all the tributes, Carter told ET that there was one that really stood out.

WATCH: Leonardo DiCaprio Remembers 'Growing Pains' Co-Star Alan Thicke

"I think Leo's," he revealed. "Leo's tweet, the press release the day before was really, really beautiful, and he even went -- I didn't even have his number -- he went out of his way to send me a text. I think his was really, really touching."

Hear Leo's full tribute to Alan in the video below.