Wilson scored 19 goals in the Championship last term and played a vital role on their route to the Playoff final at Wembley.
He told Liverpoolfc.com: "I feel I gained massive experience under a fantastic manager in Frank Lampard, who gave me the opportunity to go out and play week in, week out, express my ability and go out there with no fear. I felt confident throughout the season.
"To finish in the playoff places and then to have a great two games against Leeds to get us into the playoff final was great. We couldn't quite do it in the final, which would have been really nice, but all in all it was a great season.
"I loved my time at Derby, it is a fantastic club. Last pre-season I had a few clubs who wanted me, but it was up to me, the club and my agent to come up with the right club. We felt we did that in Derby. I went there, played a lot of games and had a really good season both personally and as a team, so I am really happy with the way it went.
"I'm disappointed we couldn't win the playoff final and get into the Premier League, which would have been an added bonus but unfortunately it wasn't to be."