Mohsen Ghailan and Malek Naser Harharah were among eight Britons and two Algerians convicted in the southern city of Aden of charges of associating with armed groups, plotting murder and destruction and possessing weapons.
The prosecution also alleged the men were linked to an Islamist group responsible for kidnapping 16 Westerners in December 1998. Four of the captives died in a botched rescue bid.
Three of the Britons were released just over a month after the 1999 trial, having being sentenced to time already served.
A fourth was released in 2002 after serving three years, and two more were freed last December after serving their sentences.
The Britons have maintained their innocence and some have even alleged their confessions were extracted by torture.
The two Algerians remain in jail.
The last two Britons were released before completing their full seven-year sentences reportedly in a "goodwill gesture" from Yemen.