The town is situated in the Fowey river valley, positioned between the A390 road from Tavistock to Truro and the upper tidal reaches of the river.
Lostwithiel railway station is on the Cornish Main Line from Plymouth to Penzance. It is situated on the south side of the town, just across the medieval bridge. The line was originally built for the Cornwall Railway which built its main workshops here, but the surviving workshop buildings were transformed into apartments in 2004. A branch line takes china clay trains to Fowey.
The town contains the suburbs of Bridgend to the east and Rosehill and Victoria to the west of the River Fowey.
