The Northern Ireland Football League Championship (known as the Playr-Fit Championship for sponsorship reasons) is the second level of the Northern Ireland Football League, the national football league in Northern Ireland. Clubs in the Championship can be promoted to the highest national division – the NIFL Premiership, and relegated to the third level – the NIFL Premier Intermediate League.
In its current format, it was founded in 2008 as the Premier Intermediate League for members of the previous IFA Intermediate League that met the new stricter membership criteria, though was marketed as the IFA Championship. In 2009, it was extended to two divisions: Championship 1 and Championship 2 with promotion and relegation between the two. In 2013, the Championship and Premiership became part of the Northern Ireland Football League, independent of the Irish Football Association (IFA).
Under reforms agreed by NIFL clubs in 2014, Championship 1 acquired senior status from the 2016–17 season onwards, continuing as the NIFL Championship. Championship 2 became the NIFL Premier Intermediate League, retaining its intermediate status.
The second level in Northern Irish football was known as the B Division from 1951 to 1995, the Irish League First Division from 1995 to 2003, the Irish First Division from 2003 to 2008, and the IFA Championship from 2008 to 2013.
The B Division of the Irish League was founded in 1951, and originally consisted of the reserve teams of the senior Irish League clubs alongside some of the top intermediate clubs. It effectively replaced the Irish Intermediate League, which had been the de facto second tier league below the Irish League since 1915. The Irish Intermediate League continued alongside the B Division until 1954 when it ceased to exist and its remaining clubs joined the B Division.
The B Division was split geographically into North and South sections in 1974 (with a play-off to determine the winners in 1974–75 and 1975–76), and then into Section 1 (containing the intermediate clubs) and Section 2 (the reserve teams of senior clubs) in 1977. There was no promotion to the senior Irish League, although clubs could be elected to the senior league; Larne were elected in 1972 to replace Derry City, Carrick Rangers and Newry City were elected in 1983 when the Irish League expanded from 12 to 14 clubs, and Ballyclare Comrades and Omagh Town in 1990 when the league expanded to 16 clubs.
A new second tier was created in 1995 when the Irish League split into a Premier Division and First Division, each with eight clubs and automatic promotion and relegation introduced. In 2003 the Irish Football League was wound up, with the top division becoming the Irish Premier League and the second division becoming the Irish First Division. This continued for five seasons, until the NIFL Championship was created.