Doherty got emotional with Entertainment Tonight on Sunday when addressing her former co-star's medical scare.
"I can't talk about it here 'cause I will literally start crying but I love him and he knows I love him," Doherty said. "It's Luke, and he's my Dylan."
Doherty revealed that she has been "in contact" with Perry and said that his family, friends and fans should "just keep [sending] positive wonderful thoughts."
Perry, 52, was hospitalized on Wednesday after reportedly suffering a stroke. He was transported to a nearby hospital after police responded to a call at his home in Sherman Oaks, California.
"We received a 911 call at 9:39 a.m. yesterday," a spokesperson for the Los Angeles City Fire Department told ET on Thursday. "The firefighters and paramedics from our department responded and one ambulance transported to an area hospital."
A representative for Perry has since said that he is under observation at the hospital.
TMZ reported Thursday afternoon that Perry was put in a "medically induced coma," but a rep later said Perry was sedated and not in a coma.
Many of Perry's co-stars, both past and present, have taken to social media to share their support for him.
"My friend. Holding you tight and giving you my strength. You got this," Doherty wrote on Instagram alongside a photo of them from 90210.
"No words can express what my heart feels hearing today's shocking news. Let us all say a prayer for his speedy recovery," Ian Zeiring wrote.
"Thinking of you, Luke. And praying for your safe recovery," Lili Reinhart, who plays Betty Cooper on Riverdale, wrote. She added a selfie with Perry, who plays Fred Andrews on the Archie Comics-inspired CW drama.
Perry's reported stroke happened the same day FOX announced a Beverly Hills, 90210 revival featuring most of the main cast returning to play fictional, "heightened versions" of themselves trying to stage a 90210 reunion. The event series will run six episodes this summer. Doherty and Perry were not reported to be included in the revival.