A church has been here at least since 1021 when the advowson was given to the Abbey of Ely, passing to the Bishop of Ely in 1109. Nothing visible survives of that church, and the earliest part of the present building is the tower, built in about 1300. The rest was destroyed by an inundation from the sea in 1337. Rebuilding started soon afterwards, but was interrupted by the Black Death in 1348. 

As finally realised, the church is a magnificent demonstration of late medieval local agricultural wealth, 161 ft in internal length. The upper stages of the tower and the nave date from about 1360 and the long chancel from about 1425, the latter built probably at the expense of the Rochford family, some of whose members are buried in the Lady Chapel, and whose shield is over the southern entrance to the passageway below the high altar. The south porch was added in about 1435 (it includes the coat of arms of Sir John Goddard, who died that year), while the north porch is possibly slightly later.

In 1561 the advowson was passed to the Crown. The ornamental embattled parapets are said to date from 1634, and are just one of several notable seventeenth-century interventions, including a screen across the west end, the elaborate font cover, the pulpit and benches in the nave and aisles. The chancel roof and south aisle roofs were replaced and releaded in 1812, and the church was restored in 1898 and again in the early twentieth century, when the floor was lifted and the seating rearranged.

The church has never failed to elicit superlatives. For Simon Jenkins, it was ‘the Queen of the Marshlands…St Peter’s is to west Norfolk what Salle is to the east, a church for the connoisseur of this noble county’. He gives it five stars, one of only eighteen of his thousand best churches to be awarded that accolade, and the only one on Norfolk. 

In a county of magnificent medieval churches, John Betjeman considered it ‘perhaps the finest’, and this view was also shared by H. Munro Cautley. Pevsner & Wilson went further and thought that ‘Walpole possesses one of the most impressive churches of its date in the country’ and Alec Clifton-Taylor concurred: ‘Among village churches it would not be easy to find a more beautiful example of the style than Walpole St Peter in Norfolk […] It is the ensemble … which offers such a wonderful and, once seen, unforgettable aesthetic experience’. 

The fact that (the tower apart) it was rebuilt in one almost continuous programme gives it a degree of architectural cohesiveness not common in medieval English parish churches. This architectural unity combined with its cathedral proportions, exquisite carved detail and wealth of furnishings give the building undoubted high archaeological, architectural and historical significance. This is reflected in its Grade I listed status, a category enjoyed by only about 2.5% of listed buildings.