Portsmouth lifted the FA Cup for the first time since 1939 after Kanu proved to be their hero once again in a 1-0 win over Cardiff at Wembley.
The gangly Nigerian striker scored the goal which earned Pompey a 1-0 win over West Brom in the semi-final - and he pounced after 37 minutes of Saturday's final with the Bluebirds, stabbing home from close range after Peter Enckelman had spilled a right-wing cross from John Utaka.
Kanu also wasted the game's other clear-cut chance on 22 when he rounded Enckelman and Glenn Loovens before hitting the upright from a tight angle.
And it was defender Loovens who went closest to an equaliser for Dave Jones' troops, chipping the ball into the net on 45 only to see referee Mike Dean rule the goal out for a handball offence.
Portsmouth manager Harry Redknapp described the victory as a "dream come true".
Redknapp told BBC Sport: "It's fantastic for everybody - my family, the players, it's great. It has been a difficult year off the field so to win the FA Cup is a dream come true.
"Cardiff were putting us under pressure, putting balls in the box, they played well and worked hard.
"When we get in front we're difficult to break down and the defence were terrific."
Goalkeeper David James added: "It was another hard game, a bit scrappy again but we deserved to win.
"The lads held tight, we've only conceded one goal in the whole competition and we've been good."
Asked about his manager Redknapp, James said: "Harry's a legend now isn't he? Hats off, well done Harry."
Defender Sol Campbell, part of the Pompey defence that withstood some late pressure from the Championship side, said: "It's fantastic, this is a brilliant day for everyone who's connected with Portsmouth.
"We worked hard, we had our luck through the rounds but in the end the result was good.
"Cardiff played good football, they had good chances but I think the quality came through in the end."
Match-winner Kanu, sporting a cap with 'king' written on it, told Sky Sports: "They call me king.
"I have to deliver and hopefully I did. I have to thank God - God made it possible for me to score.
"This is the best moment of my life. I started the game and I won the cup for Portsmouth. I have felt nothing like this."
Kanu hit the post with an earlier chance, but added: "I kept going, I kept my head down and I scored.
"You have to take your chance and that's what I did.
"Portsmouth is not one of the four big clubs, no-one could believe we were going to do it and we did it."
The Nigerian now hopes to stay on with the Fratton Park club.
He added: "I hope the fans, Harry, everyone at the club will remember this day and they are going to give me a contract."
Cardiff boss Dave Jones told BBC Sport: "A slight mistake cost us, we gave it everything we've got and we've done everyone proud.
"What we have done today is prove that maybe other teams can achieve what they thought was impossible.
"I'm very proud of my players, my staff, the chairman, and especially (the fans). They have been magnificent and I'm just sad we couldn't see it through to the death for them.
"There wasn't a great deal in it, there's no-one to blame, but it's hard to swallow."
Asked whether the run to the final should be a springboard for the club to now mount a challenge for promotion to the Premier League, Jones said: "It has to be. We've struggled for two years, no money for the last two years.
"We've now got a brand-new stadium, fantastic training facilities and if we don't move on from here, we want shooting."
