An adjustable riser suspension system for suspending a riser under tension including a riser hanger, a mating sleeve rotationally coupled to the riser hanger, a ratchet-latch sleeve located inside the mating sleeve with an external profile configured to engage an internal profile of the mating sleeve and an internal profile configured to engage an externally threaded face of the riser. The riser hanger and mating sleeve are configured to move downward relative to the riser such that the mating sleeve fits over at least a portion of the riser, causing the ratchet-latch device to ratchet over the external threads of the riser. The mating sleeve is configured to rotate relative to the riser, causing the internal and external profiles of ratchet-latch device to lock the riser and the mating sleeve to prevent movement of the riser relative to the mating sleeve.