Goals from Hector Kyprianou and Ricky-Jade Jones put Posh in charge at the break, before Ryan De Havilland completed the scoring in stoppage-time.
It leaves Posh fourth in the League One table and keeping up the pressure on the top two.
Take a look at our gallery of fans at the game and see if you, or anyone you know, features.
Get the latest Posh news, here.
1. Posh 3 Oxford 0
Peterborough United fans enjoy the impressive win over Oxford United. Photo: David Lowndes
2. Posh 3 Oxford 0
Peterborough United fans enjoy the impressive win over Oxford United. Photo: David Lowndes
3. Posh 3 Oxford 0
Posh v Oxford - fans gallery Photo: David Lowndes
4. Posh 3 Oxford 0
Peterborough United fans enjoy the impressive win over Oxford United. Photo: David Lowndes