Bosses at Enterprise Rent A Car want to install a 7ft-high steel fence and gates across the front of its premises in Newcastle Road, close to the Testos roundabout at West Boldon.
They insist they have been driven to act only as a precautionary measure to secure the vehicle storage area and as part of a branch-wide upgrading scheme.
The Leeds-based company has now lodged an application to build with planners at South Tyneside Council.
Operations manager Pete Cummings said: “We are busy improving security across our branch network.
“There has been nothing of specific concern around security at this location, but we would like to fence the area off.”
The 2,900sq m site, which houses an office block and vehicle rental space, is currently surrounded on some sides by a low natural stone boundary wall.
Enterprise Rent A Car plans for the existing boundary to remain in place and be independent of the Paladin steel fencing, which will have a black powder coated paint finish.
The company says the upgrade would not impact on any existing public rights of way within the Fellgate and Hedworth ward of South Tyneside.
People can comment on its plans until Thursday, January 11.
The US-owned firm has around 420 branches across the UK, including in Sunderland and Newcastle, and over 7,600 worldwide.