The 42-year-old star - who has children Apple, 10, and Moses, eight, with estranged husband Chris Martin - has confessed to taking the Class A drug at some point during her life but didn't go into detail about the situation.
When asked what the hardest drug she has ever taken was during an appearance on Watch What Happens Live's Plead the Fifth segment, she replied: "Ecstasy."
The blonde beauty had a slight smirk on her face after giving the answer but didn't elaborate on the topic.
Show host Andy Cohen then said: "Very good. She didn't plead the fifth everybody."
The star was also asked who she would prefer to be stuck in a lift with out of Angelina Jolie and Jennifer Garner and while she tried to avoid choosing between the actresses at first, she eventually settled on the 'Unbroken' director and admitted it would be a great opportunity to get to know her more.
Elsewhere on the show, the 'Mortdecai' actress also admitted the best perk about being pals with Beyonce Knowles is that she has a good friendship with someone who knows what it is like to live in the public eye.
When asked to name the best thing about being friends with the 'Crazy In Love' hitmaker, she replied: "The best part about being friends with Beyoncé.
"The greatest perk of being their friend is that I have a relationship with people who are also - who are similar.
"Obviously I'm not as famous or successful as they are. But I do have a life in the public eye and I have people to sort of walk through life with in that capacity, and they're very kind and loving people."
Gwyneth also admitted she loves spending time with the couple's three-year-old daughter Blue Ivy.
She said: "And it almost means I get to be around their daughter, who I love so freaking much."