If the comparator can supply enough current, and the supply voltage is high enough to operate the LED, it will work without the transistor driver.
Calculate the resistor value by taking the difference between the comparators output high voltage and the LED forward voltage, divided by the LED current.
Without seeing your diagram, I would warn that some comparator ICs have open collector outputs so they can't directly supply any current at all. If this is the case, consider swapping the comparator inputs so the 'logic' is reversed then sink current from supply into the comparator output instead.
Brian.