Here are 17 photos from our archive from that memorable day in the Midlands.
1. Tony Agana gets past the Leicester keeper to score United's third
Sheffield United v Leicester City - 5 May 1990 Photo: Sheffield Newspapers Ltd
2. Brian Deane scores United's second goal
Sheffield United v Leicester City - 5 May 1990 Photo: Peter Tuffrey
3. Celebrations in the dressing room
Sheffield United v Leicester City - 5 May 1990 Photo: Peter Tuffrey
4. Celebrations on the pitch after promotion
Sheffield United v Leicester City - 5 May 1990 Photo: Peter Tuffrey