Brechin closed the gap on second-placed Stirling Albion with a well-deserved triumph at Central Park.
City striker Ian Russell grabbed his second double in consecutive matches to finish off the Fifers.
Russell opened the scoring in the 29th minute when he hooked the ball into the net from 10 yards.
Russell struck again seven minutes after half-time with a low shot and the points were secured when substitute Steven Hampshire added a header.
Cowdenbeath: Hay, Baxter, Hannah, Hill, Ellis, Docherty (Patrick Scullion 66), Fusco, Fotheringham, Ramsey (Weir 46), Buchanan, Clarke (Smart 66). Subs Not Used: Davidson, Allison.
Brechin City: Nelson, Richard Walker (Geddes 81), Scott Walker, Archibald, Murie, Steven Ferguson, Callaghan, King, Smith, Connolly (Hampshire 70), Russell (Devlin 81). Subs Not Used: Stuart Ferguson, Hillcoat.
Goals: Russell 29, 52, Hampshire 80.
Ref: A Law