The Scotsman has stated that the new Gunners custodian will prove himself as one of the world’s best.
The Czech Republic international signed for the North London club from cross-town rivals Chelsea over the off-season and is widely being regarded as the missing puzzle piece for the title-chasing Emirates Stadium outfit.
However, Cech had a debut to forget at the weekend, as the veteran did not cover himself in glory as Arsenal slumped to a shock 2-0 home defeat to West Ham.
Despite the new man not fully endearing himself to the home faithful on his Gunner Premier League bow, Souness has rushed to his defence.
"Don't judge him after one game," Souness told Sky Sports.
"Arsenal will not be far away again, Petr Cech will still be one of the best goalkeepers in the world come the end for the season, and he will prove that.
"I am standing my ground on a very solid platform. He has never been anything other than a top class goalkeeper, and he will continue to be just that."
Arsenal have had issues between the sticks for a number of seasons, with Wojciech Szczesny sent out on loan for this season after a number of mistakes in 2014-15 and David Ospina relegated to back-up option upon Cech’s arrival.
The Gunners have a sense of deja vu after another opening day defeat in a Premier League season where the North Londoners were desperate for a good start to the campaign.