The striker, who lifted the League Two title with the Bayview club, took to social media on Thursday to confirm his departure.
Smith joins Ross Davidson and Aaron Dunsmore in leaving the club.
The 35-year-old, who will be honoured by the club this summer with testimonial events, said: “The time has come for me to move on from East Fife FC.
"A special mention to the supporters who were amazing from day one and have given me memories that will last a lifetime.
"I look forward to seeing a few familiar faces at the testimonial events later in the year.”
Since leaving Bayview, Dunsmore has signed for Stirling Albion.