2018–19 South West Peninsula League Premier Division

The Premier Division will feature 20 teams, the same as the previous season, after Plymouth Parkway were promoted to the Western League Premier Division, and Stoke Gabriel were demoted to Division One East.

Two new clubs joined the league: Reserve sides are not eligible for promotion to Step 5.
 * Elburton Villa, promoted from Division One West.
 * Millbrook, promoted from Division One West.