Lyrics:

A letter once a year
To let you know whether I'd been good
And all the kids at school said you're not real
But I know the truth
Nobody, nobody, nobody else

Only Santa knows when you're asleep
Only Santa knows what cookies you leave
Only Santa knows if you really do believe
Only Santa knows

I saw you cross the moon
I ran inside to go straight to bed
In the magic of the night (magic of the night)
I close my eyes and watch reindeers fly
Nobody, nobody, nobody else

Only Santa knows when you're asleep
Only Santa knows what cookies you leave
Only Santa knows if you really do believe
Only Santa knows

I can't wait 'til Christmas morning before the day's begun
I'll check the garden to see if all of the carrots are gone
Tell mom and dad that we got presents
Underneath the tree, we'll have to wait and see

'Cause only Santa knows when you're asleep
Only Santa knows what cookies you leave
Only Santa knows if you really do believe
Only Santa knows

Only Santa knows
Only Santa knows

(He's on the roof)