The Blues beat Cheltenham 6-1 on the final day of the campaign to be crowned champions, having only topped the table for 32 minutes throughout the entire season.
Scroll down and click through the pages to see all the best celebratory pictures from the day...
1. Pompey celebrate their dramatic League Two title triumph
Fans invade the pitch after the 6-1 victory. Photo: Joe Pepler
2. Pompey celebrate their dramatic League Two title triumph
Fans invade the Fratton Park pitch. Photo: Joe Pepler
3. Pompey celebrate their dramatic League Two title triumph
Fans invade the pitch after the final whistle. Photo: Joe Pepler
4. Pompey celebrate their dramatic League Two title triumph
A view from the Fratton End as fans invade the pitch at the final whistle. Photo: Harry Murphy