The group, which is based in 1000 Lakeside, Northarbour in Portsmouth, trades from 209 sites across the south of England, with stores throughout Portsmouth, Southsea, Havant, Gosport and Fareham.
Bosses reported a six per cent increase in like-for-like sales across its stores in the three weeks to January 6, 2018.
The firm also reported that its total sales increased by eight per cent in the same period.
The biggest boost was seen during the Christmas week itself.
During this time the society grew its like-for-like convenience store sales by 12.2 per cent,
A high number of customers picking up their last-minute Christmas shopping saw trade build steadily for the company in the run-up to Christmas Day.
Southern Co-op chief executive Mark Smith said: ‘We are delighted with these Christmas trading results.
‘We set ourselves some particularly tough targets this year to deliver the best possible service to our customers at Christmas.
‘Our colleagues rose to the challenge brilliantly as we met significantly more of our customers’ festive top-up shopping needs than last year, in a fiercely competitive market.
‘These very positive results also reflect the continued development of our Co-op own brand product range and increased Southern Co-op social media activity in the run-up to Christmas.’
The society revealed a total year-on-year sales growth of 6.5 per cent, with a 3.2 per cent like-for-like increase, in its convenience store business for the 13-week period which ended January 6.