The two sides said the deal was reached in the early hours Monday morning.
Union members are expected to vote on it Tuesday.
Leaders of UFCW Canada Local 401 said they will recommend approval of the proposed new contract.
"The new agreement will present employees with a number of significant improvements over and above the company's last offer," the union said in a posting on Facebook, without giving details.
Meanwhile, it said its 8,500 union members who went on strike Sunday will remain off the job for now.
"Picketing will continue and Superstore employees are asked to maintain picket lines," the union said in its posting.
"As details of the tentative agreement are finalized and a plan for a smooth return to the stores is considered, it is important that Loblaw continue to understand that we are committed to bargaining strong together until a new deal is finalized."
Stores affected are in Edmonton, Calgary, Red Deer, Grande Prairie, Lethbridge, Fort McMurray, Medicine Hat, Lloydminster and Camrose.
Loblaw said its 55 Superstore and Liquorstore stores in Alberta remain open, with superstore locations operating daily between 8 a.m. and 10 p.m. and Liquorstore locations between 10 a.m. and 8 p.m.
Loblaw Companies Ltd. is Canada's largest food retailer.