The Braintree branch line is a railway branch line in the East of England that diverges from the Great Eastern Main Line at Witham and runs north-west to Braintree. The route is 6 miles 30 chains (10.3 km) in length and there are five stations, including the two termini. The line is part of Network Rail Strategic Route 7, SRS 07.06, and is classified as a London and South-East commuter line.

The stations and all services are currently operated by Greater Anglia. As of 2019 the typical off-peak weekday service-frequency is one train per hour in each direction. The timetabled journey time between Witham and Braintree is 16 minutes.

Originally constructed from Maldon to Braintree via Witham, only the line from Braintree to Witham remains open. The line was proposed by the Maldon, Witham & Braintree Railway (MWBR) and given royal assent in June 1846. The MWBR was subsequently purchased by the Eastern Counties Railway (ECR), and the line opened in 1848.

The section from Maldon to Witham was constructed as double-track, however one track was lifted during the period of the Crimean War (1854–56) and sold to the War Office.

The Bishop's Stortford–Braintree branch line, built by the Great Eastern Railway (GER), was opened in 1869. This created a route from Maldon through to the West Anglia Main Line.

The line was extended from Maldon to Woodham Ferrers in 1889.

In 1923, both lines became part of the London and North Eastern Railway (LNER).

During the Second World War passenger services on the section between Maldon East and Heybridge and Woodham Ferrers were withdrawn and never reinstated.