L.A. selected Robinson with the No. 2 overall pick in the 2014 NFL draft out of Auburn.
The Lions officially announced the trade, as well as the signing of former Buffalo Bills second-round pick Cyrus Kouandjio to beef up the offensive line.
Robinson's departure was confirmed by the Rams, and general manager Les Snead said the following about the move:
"Since we drafted Greg, he has been committed to our organization, his teammates and community outreach. We appreciate his dedication and the effort he's put forth over the past three seasons. We wish him the best as he embarks on this new chapter."
After the trade, Robinson said "I plan on benefiting from (my fresh start) tremendously. It’s really refreshing and I plan to make the most out of it," per Dave Birkett of the Detroit Free Press.
The acquisitions of Robinson and Kouandjio come after it was reported by NFL Network's Ian Rapoport last week that starting left tackle Taylor Decker will miss four to six months with a torn labrum.
While Detroit signed Ricky Wagner during the offseason to be the starting right tackle, Decker's absence leaves a major hole on the left side that could be filled by Robinson or Kouandjio.
The 24-year-old Robinson started 42 games in the three seasons with the Rams, and the bulk of his appearances came at left tackle.
Although he never lived up to his lofty draft status, the Lions surrendered little in order to roll the dice on Robinson living up to his potential.