All-rounder Procter, 28, hit 822 runs and two centuries batting at three during 2016 and played in every County Championship game.
Spin bowler Parkinson, 19, made his Red Rose debut in June against Warwickshire where he took a first innings' 5-49.
"I couldn't be happier to sign a new deal. I've really enjoyed my first full season as a professional," he said.
Procter added: "Playing for Lancashire is all I've ever wanted to do, so to sign a new two-year contract is fantastic. I've enjoyed the responsibility of batting at the top of the order this summer."
Lancashire pair Luke Procter and Matthew Parkinson have both signed new two-year contracts.