A fine Sam Saunders strike gave the Bees a deserved interval lead, and although they failed to press home their dominance, it looked likely to secure a second consecutive league win.
But Carayol's 18-yard shot levelled the scores with six minutes remaining.
And although chances came at both ends in a frantic finale, neither team had the composure to take them.
The Bees, who had lost four in a row before Saturday's win at Preston will rue their inability to take their opportunities before the break.
Dean Smith's side played with confidence and quality as they controlled possession during a stylish first-half performance in the teeming rain at Griffin Park.
Josh McEachran was the game's outstanding player, dictating the pace from the centre of the pitch along with John Swift and the ever-dangerous Alan Judge.
But it was Saunders who made the difference, racing from the halfway line and using superb decoy runs from Lasse Vibe and Judge to full effect before beating keeper Marco Silvestri with a powerful low strike.
Mirco Antenucci, on as an early substitute for the injured Chris Wood, almost levelled within two minutes when his long-range effort was kept out by a brilliant save by David Button.
But the Bees remained the more dangerous side with Judge twice going close to doubling the lead with decent strikes.
An uncharacteristic McEachran error almost presented the visitors with an equaliser, but Souleymane Doukara sent his shot just wide of the post.
But the away side's endeavour was rewarded when Carayol netted from the edge of the box.
Sam Saunders scored his first goal of the season to give Brentford the lead