Roger Ludlow (1590-1664) purchased the areas east of the Norwalk river from Chief Mahackemo of the Norwaake (or Naramauke) Indians in 1640. Ludlow contracted with fourteen men for the original planting of Norwalk. In 1649, Nathaniel Ely and Richard Olmsted became the first two settlers.

The Battle of Norwalk was part of a series of raids on coastal Connecticut towns by Great Britain during the American Revolutionary War. A total of eighty houses, two churches, eighty-seven barns, seventeen shops, and four mills were burned by the British in response to harassment from local militias. Only six houses within the business district at Head of River were spared, and George Washington described Norwalk as having been "destroyed" in his report to the Continental Congress after the battle.

On May 6, 1853, 48 passengers were killed when a train travelling at 50 mph plunged into the Norwalk Harbor off an open drawbridge. As a result of the public panic and indignation caused by the accident, the Connecticut Legislature imposed a law requiring every train in the state to come to a dead halt before crossing any opening bridge.

In J. D. Salinger's novel The Catcher in the Rye, Holden Caulfield's parents are attending a party in Norwalk the night he sneaks into their apartment to visit his sister Phoebe.

In 1827, a lighthouse was built on 53-acre Sheffield Island to mark the dangerous ledges at the entrance to the city's harbor. Archaeologists working to preserve the historic site have reported several mysterious happenings, including mystical music coming from the shores, distant cries for help, and the sound of a foghorn--despite there being no foghorn on the island. Some believe the sounds are the work of the ghost of Captain Robert Sheffield, who originally purchased the islands in the early 1800s and apparently had a knack for weird musical instruments.

The Stepford Wives (1975) stars Katharine Ross as a woman who relocates with her husband (Peter Masterson) and children from New York City to the Connecticut community of Stepford, where she discovers the women live unwaveringly subservient lives to their husbands. The climax of the film was shot at Lockwood-Mathews Mansion, a tourist attraction in Norwalk.

The Norwalk Oyster Festival is an annual fair that takes place on the first weekend after Labor Day in Veterans Park, near Long Island Sound. The festival celebrates the history of the oyster industry in Norwalk, which has been a leading industry of the town since the friendly Indians showed the first settlers the natural beds off the Norwalk shores. The average annual attendance exceeds 90,000.

In 1659, The first Meeting House was built at the present day corner of East Ave. and Fort Point St. This building was the place where the people of Norwalk worshipped on Sundays and gathered to discuss the business of the town. The building was probably made of logs and did not have a bell. Meetings were called by beating a drum.

Norwalk used to be the home of the Connecticut Wildcats, part of the American National Rugby League (AMNRL). The Wildcats won 3 championships before folding in 2015.

The Norwalk/Nagarote Sister City Project is a 35-year partnership between the people of Nagarote, Nicaragua, and the Greater Norwalk Area of Connecticut, focusing on sustainable community development and breaking the cycle of poverty for the most disadvantaged children and youth in Nagarote.