The Lee-Enfield evoloved from the Lee-Metford rifle, and earlier black powder rifle which combined a locking bolt (designed by James Paris Lee) with a rifled barrel (designed by William Ellis Metford). Lee's design was a major improvement on previous bolt-action systems. The prescence of the bolt operating handle over the trigger made it much quicker to re-load than other bolt-action rifles.

The large magazine capacity of ten rounds allowed the trained soldier to fire 15 to 30 aimed shots per minute, making the Lee-Enfield the fastest bolt action rifle of the time.

The introduction of smokeless powder in the cartridges which put greater pressure on and increased wear on the barrel rifling meant that a new square shaped rifling system designed at Enfield was introduced. This solved the problem and the Lee-Enfield rifle was born. The rimmed cartridge of the .303 was kept (and incoporporated into the design) to avoid throwing away existing stocks of ammunition and this ensured the continued existence of the classic cartridge.

The rifle was introduced in November 1895 as the .303 calibre, Rifle, Magazine, Lee-Enfield, or more commonly simply Magazine Lee-Enfield, or MLE. The next year a shorter version was introduced as the Lee-Enfield Cavalry Carbine Mk.I, or LEC, with a 21.2 inch (538 mm) barrel as opposed to the 30.2 inch (767 mm) one in the "long" version. Both underwent a minor upgrade series in 1899, becoming the Mk.I's.

In 1902 a carbine version of the original was introduced, the famous Short Magazine Lee-Enfield, or SMLE, (pronounced Smelly). The barrel length was now half-way between the original and the carbine, at 25.2 inches (640 mm). The SMLE's visual trademark was its blunt nose, the end of the barrel having shrunk into the stock.

The SMLE remained the standard British rifle during World War I and beyond. In 1926 the British Army changed the naming system and the SMLE became the Rifle No.1 Mk.III, with the original MLE and LEC becoming the Mk.I and Mk.II.

In the 1920s it was investigated how to procude the rifle in a simpler way.The number of complex parts were reduced and a new sighting system was introduced, moving it from half-way up the barrel to the receiver thus increasing its sighting accuracy. This was known as the Rifle No.1, Mk.V and later an improved fixing (the "floating barrel") to the barrel made it the Rifle No.1, Mk.VI.

The Rifle No.4, Mk.I was designed in the 1930s and features some improvements on earlier models: It was lighter, stronger and a new adjustment system for setting the "headspace", the spacing between the front of the bolt and rear of the receiver. Unlike the SMLE, the No.4 did not have a blunt nose, the barrel protruding some way from the stock. The "floating barrel" introduced in the Rifle No.1, Mk.VI. improved the accuracy and the No. 4 became the standard British rifle, with a 3x scope on the sniper version. The British Army introduced it from 1939.

Later a "Jungle Carbine" version was introduced but was soon widthdrwan from service due to accuracy problems.

In all over 14 million were produced when production stopped in 1956. The Indians continued to produce the Lee-Enfield in 7.62 mm until the 1980s.