Scotland international Cooper has penned a new five-year deal which secures the defender until June 2024 while Dallas has landed a new four-year contract to keep the Northern Ireland international at Elland Road until June 2023.
Twenty-eight-year-old Cooper’s previous deal was set to expire in the summer of 2021 with the defender having now amassed 166 outings for the Whites since signing from Chesterfield in August 2014.
Dallas joined the Whites from Brentford the following summer with the versatile 28-year-old having since made 151 appearances for the Whites in all competitions, netting 15 goals.
Dallas’s previous deal expired next summer and the duo have signed long-term deals just two days after midfielder Kalvin Phillips also signed a new five-year contract. It is understood talks had been ongoing for a couple of months with Cooper and Dallas but both players felt settled at the club and were desperate to stay at Elland Road for the long term.
With new deals signed, the pair can now concentrate fully on getting Leeds back into the Premier League with United sat third in the Championship ahead of Sunday’s return to action at Barnsley.
“I’m absolutely delighted,” said Cooper. “Me and my family are over the moon and what a way to do it with my best mate as well.
“It’s a bit of a co-incidence but as soon as Leeds wanted to extend my stay it was a no-brainer for me.
“I have had an unbelievable five years here, I didn’t start off too great but I feel like I have really come into my own the last couple of years and I’m enjoying my football more than ever.
“We’ve got a great squad here, the ambition of the club is massive and I’d be silly not to want to extend.”
Dallas added: “I’m delighted. I’m over the moon, firstly for the club to see me as an important figure and to reward me with a new contract, I am delighted with that and it’s a good feeling to commit my future.
“I have been here a while now and there’s nowhere else I want to play at. It’s where I call home, for me it’s home, for my family it’s home and I am delighted.”