During the late 17th century, a small English, Scots-Irish and Welsh hamlet grew along two old Native America trails where the Christina and White Clay Creeks turn sharply eastward toward the Delaware River. Rich soil meant wheat, corn and vegetables were plentiful, and the available ore from nearby Iron Hill fed the forges of a small country iron works. Soon a tannery and brickyard were added to the village. By 1758, the bustling local market and country crossroads received recognition in the form of a Charter from King George II, and Newark was officially born.

Schools have played a significant role in the history of Newark. A grammar school, founded by Francis Alison in 1743, moved from New London, Pennsylvania to Newark in 1765, becoming the Newark Academy. Among the first graduates of the school were three signers of the Declaration of Independence: George Read, Thomas McKean, and James Smith.

On September 3, 1777, British and American forces clashed outside Newark at the Battle of Cooch's Bridge. It was the only battle of the American Revolutionary War fought on Delaware soil and marked the first time that the Stars and Stripes was flown in battle.

During the Battle of Cooch's Bridge, a cannonball took off the head of an American soldier named Charlie Miller as he was riding through the cemetery next to Welsh Tract Baptist Church. The cannonball supposedly knocked a hole in the wall of the church. An outline of where the church was repaired is visible to this day and Miller is said to still ride his horse along Welsh Tract Road at night.

Newark is a recognized center of U.S. and international figure skating, mostly due to the many national, world, and Olympic champions that have trained at the University of Delaware Figure Skating Club and at The Pond Ice Rink. In 2009, Sporting News ranked Newark 192 in its list of the 400 Best Sports Cities.

In 1965, Joe Biden earned a Bachelor of Arts degree from the University of Delaware in Newark with a double major in history and political science, and a minor in English.

The Deer Park Tavern has been a Landmark in Newark, Delaware since 1851, but before that it was known as the St. Patrick's Inn. After lecturing at the Newark Academy on December 23, 1843, Edgar Allan Poe fell in the mud while attempting to descend from a carriage at the Inn. He was so upset that he reportedly put a curse on the building. "A curse upon this place! All who enter shall have to return!" Patrons found this so amusing that they carried Poe into the tavern with a hero's welcome. When the Inn burned to the ground a few years later, the Deer Park Tavern was erected in its place.

Before he was famous, Jamaican reggae star Bob Marley was a plant worker for Chrysler in Newark, Delaware.

Harry Coover, born in Newark, Delaware in 1917, was the inventor of Eastman 910--commonly known as Super Glue. But this was just one of his many discoveries. At the time of his death, Coover held 460 patents.

Joe Flacco was drafted by the Baltimore Ravens with the 18th overall pick in the 2008 NFL Draft, making him the highest drafted player ever from the University of Delaware. He was Baltimore's starting quarterback from 2008 until midway through the 2018 season, and helped lead the Ravens to the playoffs six times. During his tenure in Baltimore, the Ravens won the AFC North twice, appeared in three AFC Championship Games, and beat the San Francisco 49ers to win Super Bowl XLVII.