In December, Wallace pledged to the home state Louisville program.
"Probably five or six days after that, I got to thinking about things," Wallace told BSN Monday evening. "I didn't think Louisville was the place for me."
Wallace said he spoke with Colorado coaches some time last week to tell them he had finalized his decision and he wanted to be a Buffalo.
"Ever since I took my visit (to CU) I was really impressed with it," Wallace said. "Every other visit I went on, I found myself comparing it to Colorado. I think that's the place that's going to allow me to have success in the future, both academically and athletically."
Wallace said he likes the way the Buffs use several tight ends in their offense.
"I got to see it firsthand. I watched a lot of their games," he said. "They used two and three tight ends. They had a bunch of tight ends with catches. I liked how they used Tyson DeVree and Riar Geer – they both got a lot of playing time. They were both good at different things and they allowed them to do what they do best."
DeVree is out of eligibility, as is Joe Sanders, leaving Patrick Devenny, Geer and Nate Solder as the only scholarship tight ends on the roster prior to Wednesday's national letter of intent signing day.