The clothes, which included over 5,000 pairs of thermal socks, 5,000 pairs of thermal gloves and 5,000 thermal hats, were stolen from a warehouse on Danby Walk in the East End Park area of the city.
Officers believe the break-in occurred sometime between 3.30pm on Sunday 2 Sept and 3.30pm the following day at the site, which had been loaned to the charity for storage.
Along with the clothes, over 5,000 toothbrushes were also taken from the store, which was being used for storage before care packages were distributed nationally to homeless and vulnerable people in time for this winter.
Inspector Jackie Hawkes, who leads the Burmantofts and Richmond Hill Neighbourhood Policing Team, said:
Stealing anything is completely unacceptable but stealing from a charity is the lowest of the low and utterly despicable.
A lot of hard work by a lot of people has gone into raising the funds needed to buy these clothing items which are desperately needed by vulnerable people to keep them warm during the winter months.
We are working hard to find those responsible and I would encourage anyone who may have seen something suspicious in the area at the time of the offence or who has perhaps been offered any of these items for sale contacts police.
Anyone with information is asked to contact the Burmantofts and Richmond Hill Neighbourhood Policing Team via: 101 or call Crimestoppers, anonymously and in confidence, on: 0800 555 111.
Martin Campbell, Director for Community Support Projects at the charity, said:
With the shortage of hostel accommodation and various other reasons people have to sleep rough. These ‘Vinnie packs’ (named after our patron) offer a little bit of comfort to those living on the streets when temperatures plummet, a space blanket and thermal clothing can stop people getting hypothermia.