The talk show host, 56, was surprised by her longtime crush – Jackie Jackson of the Jackson 5 – while filming a segment for her Teen Heartthrobs episode.
Jackson, who popped up behind Winfrey unexpectedly at her desk with flowers while she was working and had no makeup on, says he was excited to make her dreams come true.
"It's been 10 or 12 years that she's been talking about me on her show, saying I was her favorite Jackson – I was her heartthrob," Jackson, 59, tells PEOPLE.
"My sister was on Oprah's show, and she came back and said, 'Oprah is in love with you. When she was a teenager, she had your pictures plastered all over her walls everywhere, and she thought she was going to marry you.'"
Added Jackson, "She looked up and saw me, and starts screaming. She couldn't believe it was me."
Jackson's appearance on Winfrey's show after a long haitus from the spotlight, is not the last you'll hear from him this year. He just released his first single since 1989 called "We Know What's Going On," and he's also releasing a Jackson 5 clothing line called J5 Collection.
The episode – which airs Thursday – features appearances and performances by additional teen heartthrobs of years past, including Shaun Cassidy (pictured), Peter Frampton and the Backstreet Boys, who were joined by ex-bandmate Kevin Richardson for a one-time reunion.