Khan lost his last two fights against Lamont Peterson and Danny Garcia, but in his first bout under the guidance of new trainer Virgil Hunter, the 26-year-old showed the polish and determination of his rise to world title glory years beforehand.
Opening up Molina in the first round, Khan won all 10 stanzas with lightning flurries and merciless pressure on the cut until referee Jack Reiss and Molina's corner agreed not to begin an 11th round due to the damage sustained by the 27-year-old American.
It was Molina's first defeat in 19 professional bouts, while Khan moves his record up to 27-3. The Bolton boxer may well target retribution against Peterson and/or Garcia next as he strives to re-establish himself as a world class light welterweight.
Though much emphasis was placed on Khan's possible switch to a more cerebral, defence-orientated strategy under Hunter in the build-up to the main event at the LA Memorial Sports Arena, the Englishman showed occasional glimmers of old habits in the first three rounds as he walked into clean lands while opening up the fight.
Nonetheless, for every singular shot Molina was able to get in, he took three or four himself as 'King' Khan started hot with his trademark bursts of speed and aggression.
By the end of the first, a small cut had been opened above the eye of the American and with the loud words of a bellowing Hunter ringing in his ear, Khan gradually reverted to a more patient approach as he opened up a comfortable lead in the bout.
Stunning Molina with a rugged left in the fifth, it became apparent that the home hope was tough enough to soak up the abuse for 12 rounds and suffer a more dignified decision loss if he could not shock Khan with a sudden finish.
But neither scenario would come to fruition as Khan's more measured approach to the middle rounds served to further bloody Molina.
At the end of both the eighth and ninth, Reiss and the appointed fight doctor took long hard looks at the cut whilst warning the corner that a forced retirement beckoned.
And after another one-sided round put Khan 100-90 up on the unofficial Yahoo!-Eurosport scorecard, it did not take the official or Molina's team long to agree not to let him come back out for an 11th.
Khan said after the bout: "Virgil's a great trainer and I want to thank him. He is teaching me to be patient and how to understand boxing. If I use my speed in the right way nobody in the world can touch me but I get too brave and too wild.
"When I hit fighters clean they usually go down. Maidana and Judah went down but Molina hung in there.
"He caught me with some good shots but I composed myself and took them. He's a top fighter and he's tough.
"I was never concerned about my career. I know I make mistakes and I'm my biggest critic especially after Garcia and Peterson. But if I fought Garcia today I would have knocked him out.
"Garcia was lucky that night and caught me with a good shot but I am ready to fight him again, any time any place."
On the undercard, heavyweight Deontay Wilder moved to 26-0 - all by way of KO - with a third round stoppage of Kelvin Price to end Price's own unbeaten record, while Alfredo Angulo scored a 10-round unanimous decision win over Jorge Silva in an exciting light-middleweight scrap.
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