Tennants, founded in 1970 by Evelyn Tennant, has grown organically under the leadership of the Sheppard family since 2000.
The business focuses purely on lettings, with Peter and Alex Sheppard at the helm.
It will now operate under Leaders Romans Group, maintaining its long-standing location in Eastbourne and continuing to serve the local community from its existing premises.
All current staff will remain to ensure a smooth transition for clients and team members.
Matt Light, group mergers and acquisitions director at LRG, said: “This is our third acquisition in the last month, and there are more to come in the weeks ahead.
“The acquisition of Tennants bolsters our already robust lettings market share in Eastbourne and reflects our commitment to growing our lettings portfolio.”
Outgoing owners Alex and Peter Sheppard added: “With the support of our landlords, tenants and associates, Tennants has developed to where we now believe the interests of our clients and colleagues would be best served as part of Leaders.
“We leave with the reassurance that Leaders Romans Group will provide the extra specialist knowledge, resources and services we would want to offer.”