The judges scored it unanimously in Prince Naseem's favour: 114-109, 115-110, 116-108.
But it was a messy fight with as much wrestling as boxing, and both fighters had points deducted for transgressions.
And the mood threatened to get as ugly outside the ring, with plenty of booing and some disturbances in the crowd.
Hamed failed to wow the crowd at the Joe Louis Arena in Detroit as he promised he would.
Speaking after the fight, he said Soto had came to rough him up, but he failed.
"I wasn't coming to America for nothing. It was God's will. I knew I was going to win the fight."
Uncomfortable
Hamed arrived in the arena to the Motown classic Get Ready, but from the start he looked uncomfortable against his awkward, brawling opponent.
Cesar Soto has never been knocked out in 11 years in the fight game, and in the first three rounds Hamed found it hard to break through to land any telling shots.
After a minute of the second round, Hamed took a big shot on the chin but rode it well.
It looked like things might be going wrong for Hamed in the fourth, when he had a point deducted for unsportsmanlike conduct.
And they went from bad to worse in the fifth when he threw his opponent to the ground and had another point deducted.
Hamed wasn't getting his jab working and there was a lot of holding and mauling.
However, in the middle rounds Hamed began moving a little more easily and started to take control.
In the eighth Soto had a point deducted for use of the head, and Hamed landed some blows through the Mexican's defence.
Come the ninth, Hamed was clearly growing in confidence and moving around the ring with some of his old authority.
Never knocked out
Blood was pouring from Soto's nose and Hamed clearly wanted to finish the Mexican off.
But Soto, known to his fans as Cobrito or Little Cobra is known for his solid chin and has never been knocked out in his 62-fight career.
And although Hamed was on top in the tenth, eleventh and twelfth he never looked like landing the killer punch.
As many boos as cheers greeted the final bell.
But Hamed was unrepentant after the fight saying he had what he wanted - the WBC title - and was now ready for the next fight.
He remains unbeaten after 33 fights, with 24 wins inside the distance.
Naz acknowledges the Prince
(23 Oct 99 | UK)
Hamed prevails in the eleventh
(10 Apr 99 | Sport)
Hamed's unification aim
(16 Feb 99 | Sport)
Naz goes it alone
(23 Oct 99 | Sport)
Prince Naseem Hamed
Hamed v Soto (HBO)
Boxing Monthly
BBC Radio 5 Live
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