The Riders won 73 - 61 against the Lions following the two-legged clash between the 1st and 8th seeds in the BBL championship.
Anthony Rowe top scored in Leicester hitting 24 with team-mate Drew Sullivan getting 23 of his own.
That gave the Riders a 12 point lead on the night and a 14 point aggregate lead - with an overall 143-129 win.
Riders managed a 2 point victory at the Crystal Palace National Sports Centre winning 70-68 in front of a capacity crowd with Jay Couisnard hitting 17 to lead the Riders' scoring.
They would face a swift turn-around with the second leg of the play-off being the day after at the John Sandford Centre.
Riders win 73-61 and advance to the semi-final next weekend!!! #BBLplayoffs #riderupRiders started strongly winning the first quarter 19-15 to give them an overall lead of six points against the Lions.
— Leicester Riders (@RidersBball) April 13, 2013
The second was slightly closer with London equalling Leicester's 16 points to leave the score at 35-31 at the break.
The London Lions pushed Leicester Riders in the third but Riders were displaying their championship winning quality and won the third quarter by one point; 15-14.
The fourth saw Leicester extend their lead getting 8-2 up early in the quarter and eventually won the quarter
The Leicester Riders look forward to the play-off semi-finals meanwhile, the London Lions will look ahead to the 2013/14 season at the Copperbox.
Great effort… but it wasn't to be.Lions lose 73-61 and are out of the #BBLplayoffs.*Photo is from Here.
— London Lions (@London_Lions) April 13, 2013