Hoddesdon () is a town in the Broxbourne borough of the English county of Hertfordshire, situated in the Lea Valley. It grew up as a coaching stop on the route between Cambridge and London. It is located 3 miles (5 km) West of Harlow 4 miles (6 km) southeast of Hertford, 5 miles (8 km) north of Waltham Cross and 11 miles (18 km) southwest of Bishop’s Stortford. At its height during the 18th century, more than 35 coaches a day passed through the town. It saw a boom in the mid 20th century as gravel was extracted from the area, but was exhausted by the 1970s. The lakes and water pits left behind have been used as leisure amenities. Today, Hoddesdon has a little light industry but is mainly a London commuter belt town. The town hosted the eighth Congrès International d’Architecture Moderne in 1951. It is twinned with the Belgian city of Dinant.
The Prime Meridian passes just to the east of Hoddesdon.
The town is served by Rye House railway station and nearby Broxbourne railway station.