The province's new coach Matt Williams, who spoke last week of the importance of having Ulstermen playing for Ulster, said of the signings: "It is great to secure some of our young shining lights so we can build up our squad and ensure that the home grown talent continues to pull on the white jersey."
Commenting on his new contract, powerful back rower Henry said: "I am over the moon to have signed. Obviously the start of the season was tough but things are looking a lot brighter. Matt Williams has done a great job so far and I am just so happy to be given the opportunity to stay at Ulster and be part of this bright future.
"Darren, Stuart and myself have all come through the Ulster Rugby Academy which is a great system and it is brilliant to see so many Ulster boys given the chance to play for their province."
Cave, who played for the Ireland Under-20s and 'A' team last season, was also pleased to have gained a new deal.
"Matt Williams has made a great impact on the whole squad. Matt and the rest of the management are starting to build something that I want to be a part of and I am delighted to be involved for another year," said the fleet-footed centre.