Ivory Coast international Zaha agreed a new deal at Selhurst Park earlier this month that runs until 2023, having last season helped prevent his boyhood club from dropping into the Championship.
Yet Souness has made the bold claim Zaha should be playing for a club accustomed to challenging for Europe's major honours, rather than one involved in relegation fights.
Zaha, 25, has previously spent two years at Manchester United, for whom he made just two Premier League appearances, yet ex-Liverpool, Sampdoria and Rangers player Souness is convinced the Palace forward is worthy of consideration from Barcelona or Real Madrid.
"I think he's sensational," Souness told Sky Sports.
"I can see him playing for Real Madrid, that's how good he is. I think there's maybe a handful of players who have got the change of direction and balance that he does, and I think he should get more penalties, he isn't a diver.
"I think he's got a unique talent and with the utmost respect to Crystal Palace - and maybe he's been scarred by the experience at Manchester United - he's ready for a big, big club, the biggest clubs.
"If he stays at Palace he's going to end up with no trophies and think, 'What if'.
"I think now he's ready. Even for the big two in Spain, I think both of them would welcome him with open arms, he's a door opener, and there isn't too many of those players around.
"He's unique in our football. He's in that league, he's got the stuff that gets you on the edge of your seat."