The defensive midfielder was unveiled as the Rams' fifth summer signing on Tuesday morning, penning a three-year deal at Pride Park for an undisclosed fee.
New boss Lampard has already brought in Harry Wilson, Mason Mount, Florian Jozefzoon and Jack Marriott since replacing Gary Rowett in May, and the Chelsea midfield legend admits that the addition of Evans provides some much-needed balance.
"George is a very good player and arrives here at a good age as well," he told the club's official website. "I worked with him when I was at Manchester City - he was training with the first team regularly at the time – and he impressed me with the way he played, as well as his attitude.
"George has fantastic attributes and will be of benefit to us both on and off the pitch. We need the correct balance in the team and I have been fortunate to bring in some excellent attack-minded players this summer, but George will give us security in terms of his defensive nature.
"He's very comfortable on the ball and can move it quickly, which is something that we are looking for. At 23 years of age, with Championship experience at Reading and the upbringing he had at Manchester City under his belt, I believe he is a great addition to our squad."
Evans could make his debut for Derby in Friday night's Championship opener against former club Reading.