There is some evidence that Westley was known to the Romans but the earliest mention is in a document of around 1040 giving Westley village to the Abbey of Bury St Edmunds. Another very early record of the village is contained in the Domesday Book where there is reference to Westlea as the village was then known. It is recorded as sold by Richard, son of Count Gilberd including a church and 8 acres.
In 1674 the population was 60-70. By 1821 the population had increased to 124 in 26 houses. By 1831 there was a small increase to 132 in 27 houses. The population has seen gradual growth over a long period of time. By 2001 the number of residents is recorded as 189.
The village was once considerably larger in area, much having been absorbed into Bury St Edmunds after World War II. In times past there were three manors. Sextons Manor is now part of Bury St Edmunds and is close to the town’s barracks. Pembroke (or Dunham Hall) has been lost but is thought to have stood just south of Old Church Lane near what is now Parson's Barn and Luce’s (or Leo’s) Hall was situated where Westley Hall now stands.
The ruins of St Thomas the Martyr church can still be found in the old churchyard at the western end of Old Church Lane. Reputedly destroyed by a fireball or lightning in 1744 when the tower collapsed, the church was abandoned and much of the stonework pillaged in the early nineteenth century. The new church, St Mary’s, was funded by public subscription with a significant contribution from the Marquis of Bristol. His influence caused it to be positioned where it could, at the time, be seen from Ickworth Park. St Mary’s was licensed in 1835 and in the past decade has been the subject of considerable restoration. It is one of the earliest concrete buildings to have been built in England.
During the First World War the village’s claim to fame was to be bombed by a Zeppelin and during the Second World War it was home to a Lysander airfield, though that is now the Westley Estate of Bury St Edmunds.
Sunset at Westley