The chapel was built with a ridge-pole roof, and loops set into the roof timbers were once used to hang fishing nets and other tackle over the winter months, a reminder of the building's practical origins among seasonal fishing communities. It has no porch or sacristy, reflecting its simple, functional beginnings.
Inside, the pulpit is of Renaissance type; one source suggests it was likely made on site in 1767. The altarpiece, an oil painting on wood, depicts the Last Supper. A wooden panel bearing a devotional inscription hangs on the south wall, possibly dating from the 18th century.
The chapel's interior wall paintings are attributed to Olof Gåhlin and are said to date from 1711, a time when Trysunda was reportedly used as a naval base by Karl XII; it has been suggested that Gåhlin may have been a craftsman aboard one of the warships anchored in the harbour, though this remains uncertain. The paintings on the north wall draw on Old Testament scenes, while those on the east and south walls depict New Testament subjects. The west wall shows Saint George fighting the dragon. The roof itself remains unpainted. According to one account, the chapel was originally painted red and stood out as the only painted building on Trysunda; it is now clad in white-painted standing panelling. A significant renovation in the early 1930s uncovered the wall paintings within the church.
Trysunda has two burial grounds: a small churchyard immediately surrounding the chapel, and a larger one established in 1949 in a pine grove a short distance into the island.