Issam Jemaa was the star of the show for the defending champions on Tuesday as he bagged a first-half hat-trick to set up a semi-final clash with New Bengal.
They had the tie wrapped up by half-time and, despite going down to 10-men in the second-half, they were able to stroll into the last four.
Leading 4-2 from the first leg, the Kuwaiti champions took 15 minutes to open the scoring in Kuwait City through Abdullah Al Buraiki.
The midfielder picked the ball up on the halfway line before beating three players and unleashing a 25-yard strike that Imran Mohamed could not get close to.
Jemaa struck his opening goal 14 minutes later with a fantastic strike from the edge of the penalty area. He cut in from the right-hand side and fired a left-footed shot into the top corner of Mohamed's goal.
With the half coming to an end, Jemaa struck twice to complete his hat-trick. The second came from the penalty spot - although the striker had to convert at the second attempt.
His treble was completed on the stroke of half-time as he rose to head home from close range to net his seventh goal of the tie.
Early in the second half the hosts were reduced to 10-men when Yaqoub Al Taher was dismissed for a cynical foul on Ali Ashfaq. The striker was clean through on goal when Al Taher hauled him down on the edge of the penalty.
After a first half full of goals the second was a much more sedate affair, with only Ali Al Kandari finding the back of the net. With 20 minutes to play the striker rose to head home Al Kuwait's fifth goal of the match and 12th of the tie.
Ali Umar created a great chance for Mohamed Hussain to get a consolation goal for New Radiant in the closing minutes, but the striker dragged his shot wide from inside the six-yard box.
