Coote was a Windsor Wolves junior and made his first grade debut as an 18-year-old with the Panthers in 2008.
He has now played 82 NRL matches, scoring 43 tries.
“I’m really grateful for the opportunities Penrith has given me,” Coote said.
“It’s been a great club to be a part of. I have made some great mates and the support from fans has been amazing.
“I’m looking forward to my next challenge with the Cowboys and I’m excited to see what they have planned for me.”
Cowboys general manager – football Peter Parr said the 23-year-old was an exciting acquisition who is readymade for NRL football next year.
“We’re very happy to have been able to sign Lachlan to a contract with North Queensland,” Parr said.
“We’re sure our members and fans will really enjoy the exciting brand of footy he plays and I know our players will enjoy having him as a teammate.
“We saw not long ago in the game at Penrith that he already has their respect for the way he has fought back from injury this year.”
Penrith general manager football Phil Moss said: “Lachlan has been a quality performer during his time at Penrith. He is one of our local juniors who has come up through the ranks and played well in first grade, but we understand players move on and we wish Lachlan the best of luck at the Cowboys and with his playing future”