The smiley dates back to a message board posting from 19 September 1982 and took six months to find.
Researcher Mike Jones searched through loads of old postings on the first ever message boards from the Carnegie Mellon University in the early 1980s.
The message he found says: "I propose the following character sequence for markers :-)."
Smileys are also known as "emoticons" and were thought up by computer users to show their feelings or emotions through typing.
There are thousands of variations now, which include abbreviations like LOL (laughing out loud).
People use them in e-mails, chat rooms and txt messages. There are even different kinds of emoticons for Japanese surfers.
If it is the first ever smiley, it means emoticons celebrate their 20th birthday next week!