Shearer, working as a Match of the Day pundit, is reported to be waiting for a call if chairman Mike Ashley decides to end Sam Allardyce's short but troubled reign on Tyneside.
But Southgate, whose position at neighbouring Middlesbrough has also been in doubt, believes a declaration of intent from Shearer would ease the stresses at St James' Park.
He said: "Sam is a very experienced manager and I think he will be able to guide them through the times they are having at the moment.
"I'm sure he could do with Alan coming out and saying 'I'm not interested' or whatever.
"I don't know if it piles extra pressure on him with Alan not saying anything.
"All I do know is that Newcastle are higher in the table than they were this time last year and I'm sure they will end up finishing higher than they did last season. For any manager it takes time to change a club around and I'm sure Sam will sort it out."