Goals from home debutant Kenwyne Jones and Ross Wallace - who was booked for removing his shirt after scoring for the third time in his career on Wearside - fired the Black Cats into a 2-0 lead with 47 minutes gone, and the game should have been well beyond the visitors as chances went begging.
Dave Kitson's 85th-minute header gave the Royals hope of an unlikely fightback, but Keane's men managed to hang on to claim a deserved three points.
Ten of the 1973 FA Cup winning team joined the players of both teams on the pitch to pay tribute to Porterfield following his death on Tuesday night, and Keane viewed what followed as a fitting conclusion to the day.
He said: "It finished the day off nicely. It was a great tribute before the game and during the game.
"The players stayed focussed and it was a nice way to finish the day off, I have to say.
"We have all done it on different occasions, paid our respects to different people over the years, and I thought today was brilliant, even during the game, and the Reading fans were brilliant as well with that.
"That round of applause is very, very good, I have to say.
"But the best way of paying our respects was to put on a good performance and win the match, so hopefully he will be looking down and would have enjoyed it.
"It's important to remember our history."