The name 'Waltham' is believed to be derived from the Anglo-Saxon words Wealt and Ham, meaning 'dilapidated homes'. The church is called St. Lawrence and thus gives the village its name. There is evidence of the existence of a Roman temple in Weycock Field in the parish. The word Weycock is thought to be a corruption of the Saxon word, Vic-cope,[citation needed] meaning 'the road on the hill'. Most of the coins found from the site are of the lower empire (except for a silver one of Amyntas, the grandfather of Alexander the Great) and the area was occupied until AD 270.

The high-road to London formerly left the London to Reading main-road at the 29th milestone and ran across Weycock Field (often referred to as Weycock Highrood). The Priory of Hurley maintained a grange in the village on the site of what is now Church Farm (to the north-west of the present Church) and this is why the great tithes of the parish were formerly appropriated to the Prior of Hurley.

Until quite recent times a large lake separated Waltham St. Lawrence from Ruscombe (the name 'Stanlake' would seem to be a survival of this) and so the southern end of the parish was known as South Lake. The Normans, who became possessed of the manor after the Conquest, gave the name of 'Sud-Lac Rue' to the area which later became known as Shurlock Row. The parish church was built where the ancient high-road entered the village.

The manor is mentioned as early as AD 940 but its continuous appearance in historical records may be said to begin with its sale by Ethelred the Unready in 1006. His widow, Queen Emma, bestowed it upon Ælfwine, the Bishop of Winchester. The Domesday Book records: "The King holds Waltham in demesne" and it remained a royal manor until 1189 when Godfrey de Luci, Bishop of Winchester, purchased it from the Crown. It was retained by the bishops of Winchester until the Reformation.

Bishop Ponet of Winchester surrendered the manor of Waltham to King Edward VI in 1551, and the King donated it to Sir Henry Neville, one of the gentlemen of his Privy Chamber, but Queen Mary returned it to Bishop John White of Winchester. King Edward's grant was confirmed (and Queen Mary's annulled) by an Act of Parliament in the first year of Queen Elizabeth I. Billingbear House was built by Sir Henry Neville in 1567, and this Elizabethan mansion existed as the home of the Nevilles until it was pulled down after a fire in the early 20th century. His son was the early-17th-century diplomat, Sir Henry Neville, junior. The parish register records that:

"September 17th, 1667, King Charles 2nd, with his brother James Duke of Yorke, Prince Rupert Duke of Cumberland, James Duke of Monmouth and many more of the nobles dined at Bellingbeare in the great Parlour".

At that time, Richard Neville was Lord of the Manor.

Henry Neville, the last heir of this branch of the family, who had assumed the name of Grey, as heir of his maternal grandfather, Baron Grey of Werke, died in 1740. On the death of his widow, who afterwards had married as her second husband the Earl of Portsmouth, the manor of Waltham St. Lawrence was inherited by Richard Aldworth of Stanlake, whose father had married the daughter and heir of Colonel Richard Neville. Mr. Aldworth, on his accession to this property, took the name of Neville.

The village school-now a County Primary School-was originally a National School with an endowment of £35 by Lord Braybrooke, a Neville descendant. The first Dame School held in the parish was held at 'Honeys'.

The village war memorial is at Paradise Corner, which takes its name from the nearby Georgian manor house, Paradise House, on The Street.