The actors met in 2005 when they were both cast in Disney's High School Musical franchise and they went public with their romance in 2007.
But, according to Eonline.com, Efron, 23, and Hudgens have called it quits.
A source tells the website's Marc Malkin, "It's nothing dramatic. There's no third party involved.
"They were together for so long. It just ran its course."
The timing of the split news couldn't be worse for Hudgens - the actress turns 22 on Tuesday (14Dec10).
Earlier this year (10), Hudgens opened up about her relationship with Efron, gushing to America's Glamour magazine, "Right off the bat, we had a connection. I think everybody could see it. When we had our audition, they paired us together. And he was adorable.
"I think that we inspire each other. (I love) having someone to grow with."
Meanwhile, in the September (10) issue of Details magazine, Efron admitted he was contemplating life as a single guy.
He said, "Everyone tells me (to play the field). I think a lot of guys would enjoy that. But I'm not really like that."