The church was built without a plinth foundation, a so-called "barefoot" church, in the second half of the twelfth century. It belongs to a small group of Njudunge churches thought to have been built by masons who moved north after the completion of Lund Cathedral, possibly connected to the nearby Nydala monastery founded around the same period. The nave and chancel, with its stone apse, date from this original building; a sacristy and timber porch were added later, and a wooden bell tower stands apart from the church itself.
Unusually for a medieval Swedish church, Hjärtlanda has seen little external alteration since the twelfth century. Only a few windows have been added over the centuries, and the building still gives a strong impression of the light and proportions of a medieval church interior, including a small communion window in the apse that was designed to create a particular visual effect inside. The original south portal has been walled up, and a doorway on the west side was opened at a later date.
According to one source, in both the eighteenth and nineteenth centuries the diocese considered closing the church, regarding it as too modest and impractical, but local resistance from the parish saved the building — a struggle credited with preserving one of the country's finest medieval churches.
Inside, the flat wooden ceiling carries late Baroque paintings from the eighteenth century, alongside earlier traces of decoration from several periods. Furnishings include a portable altar said to date from the eleventh century, from the early missionary period before permanent churches were established, along with a fifteenth-century statue of John the Baptist and a wooden madonna figure by the font, dated to the thirteenth century. A seventeenth-century pulpit in rustic Baroque style survives, and the altar itself is built directly into the apse wall. One notable find, a carved phallic figure uncovered during excavations in 1927, is now held at the Historical Museum in Stockholm rather than in the church.
The organ was built in 1880 by Carl August Johansson of Broaryd and was later renovated and enlarged in 1954.