Announcing their decision about the new product on the Sainsbury's News Twitter feed, the brand wrote: 'We've launched a new #samesex #MothersDay card to reflect the diversity of our customers and colleagues ❤️💛💚💙💜'
Customers were quick to tweet praise for the card, with one writing: 'fantastic. I love this' and another saying: 'this is great - it's so hard to find LGBT cards in shops'.
'Absolutely amazing! It may just be an 'S' on the end, but you've made 100,000s very happy,' a third agreed.
James Brown, director of commercial for Sainsbury's, said of the idea: 'From our product range to the diversity of our colleagues, we work hard to reflect the communities we serve.
'We're delighted to be expanding our Mother's Day range this year to include a same-sex card, giving our customers greater choice.'
Government statistics show that there are around 20,000 children living in same-sex couple households, and an estimated 50% of Brits send a card for Mother's Day.
Same-sex Mother's Day cards are available online, but there is said to be a limited range in stores, meaning that Sainsbury's offering will be one of the first on the high street.
The news comes just a month after the supermarket unveiled a range of same-sex Valentine's Day cards, with a design featuring two men or two women reading simply 'You + Me = <3'
James explained at the time: 'Choosing the perfect Valentine's Day card is a personal and sentimental experience, which is why we're pleased to offer new same-sex cards and give all of our love-stricken customers the ability to choose the card that's right for them.'
Sainsbury's have also featured same-sex couples in their Christmas adverts for the last two years.