The Ferrari actress revealed the story behind her tight bond with the House of Gucci star, sharing how the two became thick as thieves.
"It's like a sister," Penelope exclusively told E! News' Joelle Garguilo at the Gotham Awards Nov. 27. "It's like we can tell each other everything. We really trust each other. I've known her for 30 years."
As for the way the Hollywood icons became acquainted? "The way I met her was really special, because she picked me up from the airport on my second trip to L.A.," she recalled, "when I was there with a contract and a two-way ticket, and I didn't know anybody."
Penelope continued, "And she picked me up but she didn't let me go to a hotel. She said, 'You're coming with me to my house because you don't know anybody here,' so it really became like family from that moment." (Catch more interviews from the Gotham Awards on E! News Nov. 28 at 11 p.m.)
And it's safe to say Salma feels the same way, as the actress took to social media in April to share a video montage of the friends over the years, both on and off screen, in honor of Penelope's birthday.
The first video showed Salma and Penelope's fight scene in their 2006 film Bandidas, before it cut to a clip of Penelope talking about their bond.
"We love each other," the On the Fringe star explained, "and we don't like fighting, but we are both strong-minded people."
In one clip, Salma is also seen describing her bestie as "fantastic," "enigmatic" and "extraordinarily beautiful."
"My dear Penelope, happy birthday," Salma captioned the April 28 Instagram post. "When a new year arrives there is comfort to know that we are not alone, and you and I will have each other through this old friendship, which is the only thing getting old, because you and I aren't!"
Tune into E! News Nov. 28 for more from Penelope Cruz.