The western section of the Ringmer to Lewes Cycleway opened on Wednesday March 18.
It follows the line of the B2192 from the electricity sub-station to just before Earwig Corner on the A26.
The path turns left over Malling Down, using Mill Road to gain access to the A26 next to the traffic lights.
It can be used by cyclists, walkers, people in wheelchairs and those with buggies.
The pathway aims to make commuting by bike between Ringmer and Lewes safer.
It could also reduce congestion, particularly at Earwig Corner.
District councillor Chris Bowers road tested the cycle path on the first day it opened.
The Liberal Democrat councillor for Ouse Valley & Ringmer said he was one of the leading figures who campaigned for the cycle way after it was first mooted in the futuristic ‘Lewes Streets Ahead’ exhibition of 2002.
Cllr Bowers said: “It’s fantastic after years of hoping we could get this that it’s finally happened and it’s clear a lot of people are already making great use of it.”