The late-night host also asks the rapper-turned-actor about the epic concert prank he pulled on Ja Rule.
While appearing on "The Late Show" Friday night, the comedian and the "Power" star bonded over their admiration of the the British actress.
"Yeah, she sexy," 50 said when Colbert brought up his celebrity crush, and the late-night host agreed, "She is, she's very sexy."
"Do you know, and I'm not bragging here, I'm just speaking the truth. Do you know that I've made out with Helen Mirren?"
"I saw she kissed you on the mouth," 50 Cent said.
Back in March 2016, Mirren walked out on stage and immediately kissed Colbert right on the lips while greeting him. The CBS star wanted to know if witnessing the smooch was difficult for 50 Cent to watch, and he offered this hilarious response: "I was just wondering how your wife felt about that."
After Colbert showed the clip that was the topic of conversation, 50 Cent pointed out that Mirren knew what "she was doing."
"She knows what she's doing," Colbert agreed and then added, "I did not know what was going to happen by the way.
The "Candyshop" rapper credited Mirren's sexiness to the older Hollywood generation's "super confidence."
50 Cent, who spoke to Colbert all about his lavish lifestyle, recalled a run-in he had with his "Den of Thieves" co-star in the South of France. The actor said he saw Mirren with her husband, Taylor Hackford, who was just "there on the side."
"She needs to trade up," Colbert joked, and 50 Cent agreed, "I was just focused, man."
Colbert pointed out how his guest helped his "beef" with celebrity chef Bobby Flay during his last appearance. Since 50 Cent is the king of feuds, Colbert asked about a particular power play he threw at Ja Rule.
50 Cent explained how he purchased tickets for the first four rows of Ja Rule's concert, so it would appear as if no one showed up.
"They was, like, on Groupon for 15 dollars, it's no big deal," he joked, adding that it was a test of showmanship.
"You do not want to f--k with you," Colbert replied.
Got a story or a tip for us? Email TooFab editors at email@example.com.