The Southern League during the 2015-16 season was divided into three divisions: the Premier Division, Division One Central, and Division One South & West. Here are the clubs that competed in each division:

Premier Division

1. Bedworth United
2. Biggleswade Town
3. Cambridge City
4. Chesham United
5. Chippenham Town
6. Cirencester Town
7. Dorchester Town
8. Dunstable Town
9. Frome Town
10. Histon
11. Hitchin Town
12. Hungerford Town
13. Kettering Town
14. King's Lynn Town
15. Leamington
16. Merthyr Town
17. Paulton Rovers
18. Poole Town
19. Redditch United
20. Slough Town
21. St Neots Town
22. Stratford Town
23. Weymouth

Division One Central

1. AFC Rushden & Diamonds
2. Arlesey Town
3. Aylesbury
4. Aylesbury United
5. Barton Rovers
6. Beaconsfield SYCOB
7. Bedford Town
8. Chalfont St Peter
9. Egham Town
10. Farnborough
11. Fleet Town
12. Godalming Town
13. Hanwell Town
14. Kings Langley
15. Leighton Town
16. Marlow
17. Northwood
18. Petersfield Town
19. Potters Bar Town
20. Royston Town
21. St Ives Town
22. Uxbridge

Division One South & West

1. AFC Totton
2. Banbury United
3. Bashley
4. Bideford
5. Bishops Cleeve
6. Bridgwater Town
7. Cinderford Town
8. Didcot Town
9. Evesham United
10. Fleet Town
11. Hereford
12. Larkhall Athletic
13. Mangotsfield United
14. North Leigh
15. Shortwood United
16. Slimbridge
17. Swindon Supermarine
18. Taunton Town
19. Tiverton Town
20. Wantage Town
21. Winchester City
22. Yate Town

These clubs were part of the Southern League structure for that season, competing across the three divisions.