After a goalless first half, Amad put the visitors ahead with an excellent strike into the top corner.
Substitute Alex Pritchard then added a second before Jack Clarke completed the scoring with a low effort.
After Millwall failed to beat Blackburn, Sunderland moved into the top six and will now face Luton in the play-offs.
Here, we take a look at the best photos of Sunderland fans and players celebrating the win courtesy of our photographer Frank Reid.
1. Sunderland fans
Sunderland fans in action away at Preston North End as Tony Mowbray's side secured their place in the play-off with a 3-0 win at Deepdale. Photo: FRANK REID
2. Sunderland fans
Sunderland fans in action away at Preston North End as Tony Mowbray's side secured their place in the play-off with a 3-0 win at Deepdale. Photo: FRANK REID
3. Sunderland fans
Sunderland fans in action away at Preston North End as Tony Mowbray's side secured their place in the play-off with a 3-0 win at Deepdale. Photo: FRANK REID
4. Sunderland fans
Sunderland fans in action away at Preston North End as Tony Mowbray's side secured their place in the play-off with a 3-0 win at Deepdale. Photo: FRANK REID