The 1998–99 Northern Premier League season was the 31st in the history of the Northern Premier League, a football competition in England. Teams were divided into two divisions; the Premier and the First. It was known as the Unibond League for sponsorship reasons.

Premier Division

The Premier Division featured four new teams:

League table

Results

Division One

Division One featured four new teams:

League table

Results

Promotion and relegation

In the thirty-first season of the Northern Premier League Altrincham (as champions) were automatically promoted to the Football Conference. Chorley and Accrington Stanley were relegated to the First Division; these two clubs were replaced by relegated Conference sides Barrow and Leek Town, First Division winners Droylsden and second placed Hucknall Town. In the First Division Great Harwood Town and Alfreton Town left the League at the end of the season and were replaced by newly admitted Ossett Town and Workington.

Cup results

Challenge Cup

Featuring teams from both leagues.

President's Cup

'Plate' competition for losing teams in the NPL Cup.

Peter Swales Shield

Between Champions of NPL Premier Division and Winners of the NPL Cup.