The Latino star, who has dated Mandy Moore, Ashlee Simpson and Lindsay Lohan, admits he was turned onto the social networking website by Twitter king and That '70s Show castmate Ashton Kutcher - and now he's sure he's tweeting as much as any celebrity.
He tells BlogTalkRadio.com, "I just started Twitter a few months ago and I just reached 60,000 followers and Ashton has 11 million, but I think I'm twittering more than him now because I'm having a little more fun with it.
"Twitter is how we commune with our audience. It's fun to give them little hints about things you do during the day and have a more branded persona. It's real because it's what you're doing.
"Everyone that follows me on Twitter sends me so many sweet messages from all over the world. I'm getting people sending messages from the Netherlands, Japan, Brazil, France, Germany, Australia, Mexico and Puerto Rico, which has been a really sweet thing.
"Marriage proposals are always pretty funny, specifically internationally - because I know what they're after! Just kidding, but those are really funny."
Valderrama is particularly fond on the tweets he gets from fans who have only just started watching That '70s Show: "Some people are just starting to get That '70s Show internationally, so when they see a picture of me today and watch the show, then they think that's me now. That's hilarious because I could not look more different."