Home Bargains aims to move into the Arndale Centre by the end of May.
A tentative date of May 21 has been pencilled in for the discount store to take over the former Tesco unit.
Meanwhile work is under way at the Arndale to give the shopping centre a modern makeover.
The A-shaped metal canopy above the main Market Street entrance was removed last week and work will start on a bright new mural on the external wall of the Shoe Zone unit later this week.
Arndale owners NewRiver Retail are in talks with food and drink firms and hope to sign up new tenants for the empty units between the Arndale entrance and Subway as part of a redesigned frontage. An Arndale spokesman said talks were also continuing with businesses who may be interested in taking over the empty Travelodge units and empty units inside the centre.
Meanwhile Arndale management has stressed that the centre is very much open for business despite current road works on and around Market Street and Euston Road as part of a major Lancaster City Council street revamp.
New street surfaces have been laid at the promenade end of Euston Road and further work will continue over the coming weeks on Market Street and Victoria Street.
The work includes new surfacing, lighting, seating and signs, an overhaul of the road layout at the junction of Market Street and Victoria Street, a swap of the taxi rank outside the Arndale with the disabled bays across the road outside the Post Office, and a new turning facility for taxi cabs outside the shopping centre.