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."

Fazakerley, who has played international cricket for Guernsey, has been part of the county's academy.
"Will has had a really good season with the academy and the Second XI," chief executive Wasim Khan said.
"He has impressed us greatly with the progress he has made and it is great he is signing his first professional contract with Leicestershire."
Fazakerley's last international match was the annual clash between his home island of Guernsey and their Channel Island rivals Jersey, which they lost by 49 runs.
"I've only been there for two months and I didn't think I'd made a big enough impression there, but obviously they seem pretty happy," Fazakerly told BBC Radio Guernsey.
"I was planning to have another year in the academy, which is why I was so surprised when they offered me this deal, but obviously I won't complain.
"This is just the start, I want to have a long and successful career in cricket. I want to play as much first-class cricket as possible."
Lancashire pair Luke Procter and Matthew Parkinson have both signed new two-year contracts.
[NEXT_CONCEPT]
Leicestershire have handed 17-year-old Will Fazakerley a 12-month first professional contract.