Gallegos, 39, died at the scene. He worked at Highland High School in Salt Lake City, while serving as Cottonwood High's offensive line coach.
In exchange for his plea, prosecutors dropped misdemeanor speeding and traffic charges.
"I'm not asking for a slap on the hand," Molder told 3rd District Judge James Blanch. "I hope that one day [the Gallegos family] can forgive me for what I've done."
Molder said he woke up "every morning" with Gallegos on his mind and pledged to devote his life to treatment and speaking to others about the dangers of drunken driving.
"I know I can save a lot of people's lives and I can help other people," he said. "I think that's God's plan for me."
Debbie Gallegos, Michael Gallegos' wife, has avoided court hearings for most of the case, but said she decided to speak to Molder for the first time at his sentencing hearing because she wanted him to know the consequences of his actions. She told him of the emotional and financial burdens she and her young children were experiencing since Michael Gallegos' death.
"Hundreds, if not thousands, of lives have been affected because of that one poor decision," Gallegos said.
Molder's parents, Tim and Tammie Molder, recounted how hard it was to hear of their son being called "monster" or "murderer." They implored the Gallegos family not to view him that way.
Blake Molder is "a kid who never had a traffic ticket who made a horrible mistake," Tammie Molder said through tears.
"My wife and I, we share as much guilt in this as Blake does, and I'm sorry," Tim Molder told the family.
How much time Molder spends in prison will be determined by the Board of Pardons and Parole. He also was ordered to pay restitution in an amount that will be determined later.
After the hearing, Debbie Gallegos said she has been able to forgive Molder, but believes the sentence is appropriate.
"I just want all parties involved to be able to heal," she said.