Theydon Bois is a large residential village and civil parish in the Epping Forest District of the county of Essex, England. It is located 1.4 miles (2.2 km) south of Epping, 0.85 miles (1.3 km) northeast of Loughton and 6 miles (9.6 km) south of Harlow.
Theydon Bois is within the bounds of the M25 motorway, the outer circular road around London) and is situated near to its junction with the M11 motorway. It is served by Theydon Bois tube station on the Central line of London Underground. It lies on the edge of Epping Forest.
The parish was part of the Epping Rural District from 1894 until 1955, the Epping and Ongar Rural District from 1955 to 1974, and since 1974 it has been located in the Epping Forest District of Essex.