Ashingdon is a village and civil parish in the Rochford District of Essex, England. It lies immediately north of Rochford and 13 miles (21 km) south-east of Chelmsford. As well as Ashingdon itself, the parish also includes the small village of South Fambridge. The northern boundary of the parish is the tidal River Crouch. The Ashingdon built up area as defined by the Office for National Statistics extends beyond the parish boundary into the neighbouring parish of Hawkwell. At the 2021 census the parish had a population of 3,485 and the Ashingdon built up area had a population of 6,485.

Ashingdon and South Fambridge have been in existence for more than one thousand years and both appear in the Domesday Book of 1086, along with the Manor of Beckney within Ashingdon Parish.

Ashingdon, or, more correctly, the land to the east of the village, is the presumed site of the Battle of Ashingdon on 18 October 1016. Ashingdon Hill is the likely location of King Edmund Ironside's camp, and it faces the field of battle between Ashingdon and Canewdon. Canewdon Church sits atop another hill, and beside Canewdon village was probably the site of King Canute's camp. Early chronicles report of fierce fighting at "Hyde Wood", nearly halfway between the two villages. The parish church which lies on Ashingdon Hill, one of the parish's three hills, was built in 1020, 4 years after the battle, by the order of the king, Canute the Great of Denmark. The grade II listed parish church of Saint Andrew's is also called "Ashingdon Minster". The first priest at Ashingdon was one of King Canute's personal priests, a young man named Stigand, who 46 years later was the Archbishop of Canterbury who crowned King Harold and officiated at the coronation of William The Conqueror (William I), both in 1066. The priest appears on the Bayeux Tapestry with the caption "STIGANT ARChIEPS." The church is now dedicated to Saint Andrew, but it is believed that it was dedicated earlier to Saint Michael, who was considered to be a military saint, and churches dedicated to him are frequently located on a hill. In 2006 Southend author, poet and historian, Ian Yearsley, wrote and published a commemorative epic poem about the battle, called The Battle of Ashingdon (1016).

Ashingdon Parish was a centre of early aviation research from 1908. Britain's first aerodrome was officially opened in February 1909 and it was used for developing and flying early fixed wing aeroplanes. A few years later, early seaplanes were made there. The First World War stopped all of the aviation work until flying resumed in Ashingdon in 1919, possibly at Fambridge but also the aerodrome did move to Canewdon Road in Ashingdon, 2 miles away. The new company mainly used Avro 504 biplanes. In the early 1920s, Frank Neale started an aviation company there with a larger Avro 504 3 seater. Then in 1923, W.G. Pudney started The Essex Aviation Company flying several types of aircraft. All three firms used the Avro 504, a popular, easy and cheap to fly aircraft.

In the 1930s, the aerodrome may have moved further along Canewdon Road in Ashingdon. Some people say that it was moved by expanding into the larger adjacent field. Others say that it may have been at two separate locations in that road and others deny both suggestions and say that it was only ever at one place in Canewdon Road. The aerodrome was called Canute Aero Park, after King Canute the Great, as well as being called Ashingdon Aerodrome.

Ashingdon was the home of an aero club called "Aero 8", also home to the Essex Aviation Company, Premier Aviation and the Southend Flying Club. Many types of aircraft were designed, developed, built, flight tested and modified there, but many other types simply flew in and out of Ashingdon as a home base, way point or destination. Henri Mignet, the French designer of the Mignet HM.14 Pou du Ciel ("Flying Flea") used to visit Ashingdon for business with Aero 8 at Canute Aero Park, because they were one of the largest producers and developers of the Pou du Ciel. Aero 8's higher-powered and modified version was called "Super Pou". Several air shows took place in Ashingdon at the Canute Aero Park aerodrome. They were attended by thousands of visitors and scores of flying enthusiasts who flew in their aircraft. Later, the aerodrome moved to Ashingdon Road, then to Dalys Road, Rochford, where it was still called "Ashingdon Aerodrome". One Aero 8 Pou du Ciel ("Flying Flea") was called "Fleeing Fly".

On 20 June 1936, a DeHavilland biplane - a DH60X Moth, G-EBRT took off from Ashingdon Aerodrome in Canewdon Road and failed to gain sufficient altitude to fly over Ashingdon Minster on Ashingdon Hill. It crashed into the tall dense trees surrounding the churchyard and it came stuck intact in the branches at a height of about 10 metres (30 feet) above ground. The pilot was not injured and he climbed down the tree to firm ground. Some people in the village say that a "Flying Flea" also crashed into the churchyard trees.

Eventually, Southend Municipal Airport opened on the old Royal Flying Corps/RAF base and all flying moved to the new airport by the late 1930s. Soon it reverted to military use as RAF Rochford and it became a Battle of Britain RAF base as well as a pilot training airfield. After the Second World War, RAF Rochford became a civil airport again, now called London Southend Airport. So, early aviation has taken place at five successive locations in and around Ashingdon.