As exclusively revealed by Love Rugby League nearly two weeks ago, Carney is staying with the Red Devils.
The Australian winger was on loan at the club until the end of the season from Castleford, but will now be on a permanent deal for the rest of 2016, before embarking on another three years with the club.
“I feel right at home at Salford,”Carney told the Red Devils’ official website.
“Marwan was there from day dot for me and there are a lot of people like Dobson, Hauraki and Sa’u I have played with previously and I work well with.
“There are a lot of good people here so why would I leave?”
Salford coach Ian Watson is delighted that the winger has committed his future to the club.
“Justin is a real good bloke to have around the place. He is a great influence on the group and a hugely competitive professional,” he said.
“He wants to win things and you see that in his attacking play.
“He is a 100 miles per hour player and he is the top metre maker in the competition this year. That’s a big plus for any team.”