Before the present building, Ökna had only a modest wooden chapel, erected in 1559 for the eastern part of Alseda parish under Gustav Vasa's reign. By the eighteenth century this structure was considered too small and dilapidated, prompting the construction of a new stone church. Work began in 1766 under local master builders, and the church was consecrated in 1767 by Bishop Olof Osander.
The church is a hall church with a broad, rounded chancel to the east and a sacristy added on the north side. Its most distinctive external feature is the round tower at the west end, whose lower section may incorporate part of an older masonry bell-frame from the original chapel. The tower was not completed in its present form, with an open lantern topped by a cross, until 1837.
Inside, two ceiling paintings attributed to the painter Justelius of Eksjö and dated 1772 survive above the chancel and the gallery, depicting a woman bearing a cross and, separately, a winged female figure with a severed head. The altarpiece, painted in 1840 by Sven Gustaf Lindblom, shows the Descent from the Cross and is a copy of an altarpiece by David von Krafts in Kalmar Cathedral. The older altarpiece, depicting the Nativity, survives and is displayed on the south wall, though its artist is unrecorded. A wooden pulpit dating from 1828, the work of Israel Wennerholm, stands with a sixteenth-century crucifix mounted on the wall behind it. Fragments of the earlier church's gallery screen, carved with three apostle figures, are also preserved, mounted on the north wall.
The church's organ has a layered history: an original instrument from 1838–40 was later replaced in 1854 by a larger organ from Gothenburg, itself superseded in 1949, before a 1985 instrument reconstructed the character of the 1838 organ using surviving casework and pipework. A separate chancel organ was added in 1996.
The churchyard once held numerous wooden grave markers, a custom common in the nineteenth century; by 2019, reportedly only two of these markers remained, according to a former local curate's account.