In front of a 13,452-strong crowd, the Gunners were 3-0 up at half-time after Leeds' Lucy Ward gave Arsenal the perfect start when she could only head into her own net past keeper Gemma Fay just three minutes into the game.
It was 2-0 when Julie Fleeting put past Fay after being played in by Leanne Sanderson.
And Fay was caught out before the half ended as Rachel Yankey's free-kick from distance caught the keeper flat-footed and flew into the net.
After the break England international Kelly Smith made it 4-0 from the penalty spot after Yankey was brought down by Jess Clarke.
Sanderson turned scorer with 13 minutes left, rounding off the win by slotting the ball through Fay's legs.
It was the second trophy the Arsenal manager Vic Akers and his team have delivered to Highbury this season and their third 'double' in six years.