The Vikings announced the signing on Friday without disclosing terms. They now have eight of their 10 draft choices under contract almost two months before training camp.
The Vikings traded back into the first round to grab the safety out of Notre Dame with the 29th overall pick. Smith is expected to challenge for a starting spot in Minnesota's inexperienced defensive backfield.
First-round pick Matt Kalil and third-rounder Josh Robinson are the only remaining Vikings draft picks who have yet to sign a contract. Both have been participating in voluntary practices this week at the team's headquarters.