The former Saturday Night Live cast member, 36, proposed to model Sunshine Tutt on Christmas Eve at her grandparents' home in Gainesville, Texas, his rep confirms.
The couple met at a birthday party in Los Angeles and have been dating since spring 2005.
"Originally I was going to do something very special," Kattan tells PEOPLE. "I tried to get Bono of U2 to serenade her. That didn't happen. Then I asked Justin Timberlake. No answer. After hundreds of phone calls and text messages, I finally ended up asking one of the members of the group Hanson. He didn't want to get involved."
Instead, Kattan surprised Tutt by disguising the engagement ring in a badly wrapped, cheap box.
The couple plans to wed in 2008.
