The move follows on from a popular vote on June 18, which allows shops to open in tourist areas on Sundays, provided that they are not larger than 400 square meters.
From July 23 to August 20, Migros kept two of its stores open, in Melano and Maggia, to test the waters.
Luca Corti, communications manager at Migros Ticino, told newspaper Corriere del Ticino that the retailer has received "more than positive feedback from both tourists and residents."
He added that the results of the tests will be analysed and Migros will possibly replicate the initiative at other times of the year and at other locations across the canton.
'Adapted To Customer Needs'
Elsewhere, a Coop Switzerland spokesperson told the Italian-language daily that "it is carrying out the necessary assessments" with regard to the new opening criteria, adding that it "makes sense to have opening hours adapted to customer needs".
It seems unlikely that discounters Aldi and Lidl will be able to open on Sundays, as all its stores exceed 400 square metres.
Speaking to public broadcaster RSI, Chiara Landi of Unia, a Swiss trade union representing private sector workers, pointed out that unions had opposed this law, arguing that facilitating the opening of shops would have favoured large-scale distribution more than small shops.
"We were not surprised when we saw these 'test' openings. We know that the interests of large-scale retailers are behind the change in the law. Migros spent a lot of money in the previous campaign. We are monitoring for any abuses relating to the labor law to emerge," she added.
Prior to the change in legislation, citizens of the Ticino canton had only two options to do their grocery shopping on a Sunday – either visit a petrol station, which typically has a limited offer, or cross the border.