The centre will be expanded and modernised to care for up to 3000 abused, abandoned and injured animals each year.
When the new building is finished, there will be a cattery for more than 50 cats as well as bird, ferret and small animal rooms.
The current building will be refurbished into a two-storey kennel with capacity for up to 150 dogs plus an outdoor area to allow space for daily exercise.
The kennels will be completed with glazed doors for easier viewing for the public who visit the centre in Cardonald, Glasgow, looking to adopt and rehome the rescued animals.
Barr Construction was appointed main contractor of the project after completing four other contracts for the charity. The firm will also be installing internal and external runs and sleeping areas.
Andy Hutchison, project manager at Barr Construction, said: "We are extremely proud of our partnership with the Scottish SPCA and we're pleased to be able to provide another state-of-the-art facility for such a beneficial and worthwhile charity.
"These centres perform a vital role in their local communities and will provide care for thousands of abandoned and mistreated animals."