Laconia was established as a city in 1893. It was originally incorporated as a town in 1855 from lands at Meredith Bridge, Lakeport, Weirs, and Gilmanton. The town's name was likely inherited from the Laconia Company, an enterprise formed by Captain John Mason and the Masonian proprietors, to sell parcels of land to the original colonists during the colonial era.

Laconia is the county seat for New Hamsphire's Belknap County which was established by the legislature in 1840. Belknap county was named in honor of one of the most notable historians of the state, Dr. Jeremy Belknap. Prior to the establishment of Belknap County, the Laconia area was part of Strafford County (1773 -1841) and prior to that, it was originally considered part of Rockingham County (1771-1773). Belknap County was originally made up of eight former Strafford County towns: Alton, Barnstead, Centre Harbor, Gilford, Gilmanton, Meredith, New Hampton and Sanbornton. Today, Belknap County encompasses ten towns, including Laconia.

The area was oiginally home to one of the region's largest settlements of Native Americans, located at the point now known as the Weirs — named after the wooden fishing weirs, constructed of woven branches and set in the waterway now known as the Weirs Channel. The Weirs had been visited by Europeans as early as 1652, when the Endicott surveying party marked Endicott Rock, which is today a local monument.

The Europeans did not return to settle the area for quite some time due to a series of colonial wars being waged across northeastern America during that period. The conflicts were between the English and their Native American allies, and the French, whoh were also allied with certain Native American tribes. The last of these wars, commonly called the French and Indian War, was ended by the Treaty of Paris in 1763.

In 1727, the township of Gilmanton was granted east of the Winnipesaukee River, and, in 1746, a colonial fort was built in the area which is now Laconia. In 1761, European colonists permanently settled in the Laconia area. At that time, the settlement was known as Meredith Bridge, and was situated in what is now downtown Laconia.

Meredith Bridge was, for the most part, self-sufficient, with the settlers producing their own food, clothing, and other necessities. The main trade center for New Hampshire was Portsmouth, and Meredith Bridge was connected to Portsmouth by a road initiated by Governor John Wentworth. Wentworth wished to have a route from Portsmouth to Canada that did not include the Connecticutt River. That road is still in use today and includes Pease Road, Parade Road, Pleasant Street, Province Street and a portion of Main Street. South of Main Street, the road moves on to modern day Route 107. Starting in 1765, lumber, wheat and corn mills were established in the area of what is now Mill Street and taverns soon followed on Parade Road, most notably the Farrar Tavern in 1782, and the Davenport Tavern in 1785.

Manufacturing mills began to appear early in the 19th century. In 1800, the Bean Carding Mill was built. In 1813, the Avery Mill opened. The addition of such mills raised the importance of the thriving Meredith Bridge settlement to such a degree that it was chosen as a location for the court which was built in 1822. At the formation of Belknap County in 1840, the courthouse was designated the county court, establishing the settlement as the county seat.

In 1823, regional industrial growth, based on water power, was marked by the building of the Belknap Mill. This mill has been completely restored, but remains largely unaltered. It still stands in the heart of Laconia and is listed on the National Register of Historic Landmarks. It is the oldest such structure in the United States. The mill's water-powered wheelhouse, which dates from the early 1900s and once supplied electricity to the downtown area, is the last of its kind in America.

The early 19th century was also notable for the expansion and improvment of the regional roads, with many major routes being established.

Along with roadway improvements, this period witnessed the arrival of the first railroad. By 1849, there was rail service provided by the Boston, Concord and Montreal Railroad through Laconia to Lake Village, the Weirs and Meredith. During this same period, steamboats began appearing on Lake Winnipesaukee. The first such vessel, built at Lake Village in 1833, was the S.S. Belknap. In 1848, the Winnipesaukee Steamboat Company was formed.

Throughout the second half of the 19th century, industry grew in Laconia and the increasing labor needs of the region were met in large part by immigration of French Canadians, many settling in East Lake Village. This period also saw the rise of the tourism industry, spurred by the growth of the railroad and steamship lines. Lodging needs for tourists were met by boarding houses and large hotels. Transportation needs were met by trolley cars and the Ranlet Car Company, a builder of railcars that played an important role in the city's development by expanding into the building of trolley cars and subway cars. It eventually became the city's largest employer and operated from 1848 through the 1930s.

With the city's industrial growth came a growing need for fire protection, and early private fire brigades were set up in the city by manufacturers to protect their facilities. The services of these fire brigades were made available to the public as well. The primary motivation for establishing fire protection services was the Great Fire of November 21, 1860 which destroyed most of the property on Main Street from Mill Street to Water Street. By the 1870s, these private fire-fighting companies were well established, with fire houses, men in uniform, and state-of-the-art equipment. A horse-drawn, steam-powered water pump and its fire brigade were photographed in Laconia in 1875. Upon the establishment of Laconia as a city, the City Council voted to have the Weirs firehouse built, and that structure was complete in 1894. Early fire brigades were alerted by telegraph. Later, fire departments were alerted by telephone. During the long New Hampshire winters, fire equipment was placed on trains to move it as close to the fire as possible. It is worth noting that there were two major disasters in the early 1900's. In 1902, an explosion destoyed the Masonic temple and the adjacent livery stable. On May 26, 1903, the Great Lakeport Fire destroyed Lakeport. Fire companies were brought by train from as far away as Dover, NH, to fight the catastrophic blaze.

Electricity came to the area in the late 1800s, thanks largely to the abundant supply of water power. Horse-drawn trolleys were eventually replaced with electric models and the last horse-drawn trolley made it final run in 1898. Trolley car manufacturers continued to operate in the city until the 1930's, and other types of manufacturing remained in the area until the 1960s.

Laconia revitalized its downtown during the 60s and 70s and now the region has light manufacturing and high-tech industry as well as a solid base of professionals and service industries.