The company currently employs 500 people at premises in Glasgow, Robroyston, Livingston, Ayr, Clarkston, Hamilton, Lanark and Clydebank.
The expansion plans include new stores in Port Glasgow and Irvine, while other locations are "in negotiation".
Existing stores in Clarkston, Ayr and Livingston will also be enlarged.
The family-owned business, which is currently celebrating its centenary, has forecast a turnover of between Â£25m and Â£30m in 2015.
Its sells a wide range of products, including clothing and accessories, housewares, jewellery, watches, books, toys and confectionery.
Owner Willie Watt said: "Our business has changed dramatically since it first opened its doors in Glasgow's Sauchiehall Street, when the focus was exclusively on high-end ladies' fashions.
"We have evolved as a business and recognised that a retail offer including a wider range of great value products in a department store-style setting has greater appeal to today's consumer.
"We've seen positive growth in terms of both turnover and customer numbers, even in the recent recessionary period, and we've continued our expansion in terms of new store openings.
"My long-term plan is to have a total of 16 stores throughout Scotland, and we're constantly looking at new opportunities to secure ideal locations."

Despite taking an early lead the Teessiders were 3-2 down at half-time.
"You can't question the attitude, commitment and effort, it was first class," Agnew told BBC Tees.
"But we were a bit naive at times defensively, not just the back four, as a team. So we all take responsibility for that and look forward to Burnley."
England defender Ben Gibson was culpable for the first two goals having failed to clear, while Hull's fourth goal came as Harry Maguire was unchallenged in the penalty area.
The defeat left Boro in 19th place after 30 games, seven points behind Hull, who are one place above the relegation zone.
Middlesbrough welcome Burnley to the Riverside on Saturday.

Kengo Kuma was given a tour of the site where construction of the museum's curved inner walls is underway.
The architect said he was confident the museum would be completed on schedule at the end of 2017 and open in the summer of the following year.
It will take the remainder of 2016 to take the building up to roof height.
Mr Kuma said:  I am very happy to see the progress of the construction.
"The level of construction is very high and beautiful - it is not an easy construction because the detail is unique.
"I can feel the scale of the spaces and the scale is as I expected."
Key milestones in the first year of work included the completion of a coffer dam which enabled construction of part of the building that will sit out over the River Tay.
This year's programme involves construction of the core inner walls, stairwell and lift cores and the outer double curvature walls of the building.
Representatives from Dundee City Council and BAM Construction Ltd accompanied Kengo Kuma on the tour of the site.
Dundee Lord Provost Bob Duncan said: "People can see from the outside that something really special is beginning to take shape on this site.
"I am delighted that Kengo Kuma can see how much has been achieved here in the space of a year.
"We are delighted with the attention that this project is focusing on our city."
Pre-cast panels will be installed in 2017 to the exterior to give the building its unique slatted, multi-layered appearance.
BAM's construction manager Malcolm Boyd said: "We are relishing meeting the unique technical and construction challenges and working with all our partners to deliver a building that will inspire Dundonians and attract worldwide recognition ."
Retailer Watt Brothers has announced plans to create 350 new jobs by opening six new stores and expanding three others over the next few years.
[NEXT_CONCEPT]
Middlesbrough's defensive "naivety" cost them in Wednesday's 4-2 Premier League defeat by Hull City, says head coach Steve Agnew.
[NEXT_CONCEPT]
The architect of Dundee's V&A museum said he was "very happy" with its progress one year after the £80.1m construction project began.