The proclamation was made at St James's Palace in London.
Today, he will be proclaimed King in a series of ceremonies in the region starting in Ipswich at 1pm and a further 22 locations across the county from 3.30pm.
The Royal Family, and particularly the new King, have a strong relationship with Suffolk with dozens of visits over the years.
Here is a selection of pictures from times King Charles III visited Suffolk.
King Charles III and Queen Consort Camilla visit Bury St Edmunds for the official opening of the new Cathedral tower on July 22, 2005 (Image: Phil Morley)
King Charles III and Queen Consort Camilla visit Bury St Edmunds for the official opening of the new Cathedral tower on July 22, 2005 (Image: Phil Morley)
Prince Charles arriving for a visit of Ipswich in 1983 (Image: Archant)
A young Prince Charles during a visit to Culford School in the west Suffolk countryside (Image: Archant)
King Charles III, Colonel-in-Chief, Army Air Corps, presented Afghanistan Campaign Medals to soldiers from 3 Regiment Army Air Corps in Bury St Edmunds on July 22, 2010 (Image: Wendy Turner)
Then Prince Charles chats to crowd on his visit to RAF Mildenhall in October 1982 (Image: Archant)
King Charles III talking to some youngsters on his visit to Stoke by Nayland July 1991 (Image: EADT Archive)
King Charles III was given a tour around the Caribbean Association building and met many of the members on his tour of Ipswich in 1983 (Image: Archant)
King Charles III, Colonel-in-Chief, Army Air Corps, presented Afghanistan Campaign Medals to soldiers from 3 Regiment Army Air Corps in Bury St Edmunds on July 22, 2010 (Image: Wendy Turner)
King Charles III, then Prince Charles, on a visit to Ipswich in July 1983 (Image: Archant)
The then Prince of Wales and Duchess of Cornwall visiting Southwold in 2008 (Image: Archant © 2008)
King Charles III visiting Portman Road, the home of Ipswich Town Football Club, where he was greeted by former players Richard Naylor and Gareth McAuley among others in 2008 (Image: Archant)
Hundreds of people turned out for the Royal couple's visit to Lavenham in July 2005 (Image: Will Wright)
King Charles III at the Theatre Royal, Bury St Edmunds in 2010 (Image: Archant)
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