According to the United States Census Bureau, the town has a total area of 11.1 square miles (28.9 km²), of which, 11.1 square miles (28.8 km²) of it is land and 0.04 square miles (0.1 km²) of it (0.27%) is water. Mechanic Falls is drained by the Little Androscoggin River.

The town is crossed by state routes 11, 26, 121 and 124. It is bordered by the towns of Poland to the south, Oxford to the northwest, and Minot to the northeast.

Mechanic Falls Area Code is 207

• Town of Mechanic Falls , ME - Mechanic Falls Town Office, 108 Lewiston Street, Mechanic Falls, ME 04256
  Telephone: 207-345-2871 Fax: 207-345-9201
• Mechanic Falls Library - 15 Elm Street, Mechanic Falls, Maine 04256
  Phone: 207-345-9450
• Mechanic Falls Fire Rescue - 106 Lewiston Street, Mechanic Falls, ME 04256
  Telephone: 207-345-9896 Fax: 207-345-9201