The two sides have been hammering out the details of a contract over the past 72 hours, which was completed less than 24 hours before Saturday's annual NFL draft. Many had speculated the deal would get done by Friday evening.
Jay Glazer of FOX Sports confirmed that the deal will span six years, and is worth $78 million overall with $41.7 million guaranteed.
Last year's No. 3 overall pick, quarterback Matt Ryan (Atlanta), received close to $35 million in guaranteed pay. His contract was worth over $70 million.
The deal makes Stafford the No. 1 pick in the draft, who was the consensus top selection dating back to last November.
"I am a competitive guy; I don't think the Lions are that far off," Stafford said in an interview earlier this month with Scout.com. "Yeah, it would be a heck of a challenge to be able to go in there and make something special happen."
But with 32-year old veteran Daunte Culpepper relying upon a surgically repaired knee, the Lions were looking to address the position via the draft, and have done so with Stafford.
The team has four remaining picks in the first three rounds (20, 33, 65, 82) and will look to shore up many holes, most notably at defensive tackle, middle linebacker, offensive line, and safety.