In 1st and 2nd century, the remains of a Roman temple are dated, broken during Alamannic occupation of the Swiss plateau.
In 5th or 6th century, a first Christian church was built on this probably pre-Roman sacred area.
Ufenau is first mentioned in 741 as «Hupinauia», and in 744 as «Ubinauvia» – island of Huppan or Huphan.
Probably between 900 and 920, the early Christian church was destroyed by the Huns.
On 23 January 965, the island was given by Emperor Otto I to Einsiedeln Abbey, that still is its owner.
In 926 or some years later, St. Peter & Paul church' preceding building was given by the Hunfridings noblewoman Reginlinda and Burchard II, Duke of Swabia, in addition with a house for herself and her son Adalrich.
Reginlinda died in 958 and is buried in Einsiedeln.
In 973 later Saint Adalrich (Canonization in 1659) died on Ufenau.

Historians mention a 10th-century ferry station assumably at the so-called Einsiedlerhaus in Rapperswil – in 981 AD as well as the vineyard on the Lindenhof hill – between Kempraten on lake shore, Lützelau and Ufenau island and assumably present Hurden, which allowed the pilgrims towards Einsiedeln to cross the lake before the prehistoric bridge at the Seedamm isthmus was re-built in 1358.
In 1798 the Helvetic Republic secularized the Einsiedeln Abbey's property, and Ufenau was given to the non-durable Canton of Linth.
In 1805 Ufenau was given by the merchant Family Curti from Rapperswil to the Einsiedeln Abbey.

5800 Vitis vinifera Blauburgunder (Pinot noir) were planted in 1986.
The Einsiedeln Abbey owns 1 hectare (2.5 acres) of the Ufenau vineyards which are cultivated by its winery.

On 7 December 2003 the Ufenau association was founded, one year later «Freunde der Insel Ufnau».
Friends of Ufenau island is a booster club to finance some projects for maintenance of the buildings located on the island, including both churches, and for the restaurant's renewal.
It supports a long-time idea called «Insel der Stille» (island of silence), including a path way for disabled people around the island (completed in 2007), and regeneration of the island's shore areas to prevent increased erosion.
In 1st and 2nd century, the remains of a Roman temple are dated, broken during Alamannic occupation of the Swiss plateau. In 5th or 6th century, a first Christian church was built on this probably pre-Roman sacred area. Ufenau is first mentioned in 741 as «Hupinauia», and in 744 as «Ubinauvia» – island of Huppan or Huphan. Probably between 900 and 920, the early Christian church was destroyed by the Huns. On 23 January 965, the island was given by Emperor Otto I to Einsiedeln Abbey, that still is its owner. In 926 or some years later, St. Peter & Paul church' preceding building was given by the Hunfridings noblewoman Reginlinda and Burchard II, Duke of Swabia, in addition with a house for herself and her son Adalrich. Reginlinda died in 958 and is buried in Einsiedeln. In 973 later Saint Adalrich (Canonization in 1659) died on Ufenau. 
Historians mention a 10th-century ferry station assumably at the so-called Einsiedlerhaus in Rapperswil – in 981 AD as well as the vineyard on the Lindenhof hill – between Kempraten on lake shore, Lützelau and Ufenau island and assumably present Hurden, which allowed the pilgrims towards Einsiedeln to cross the lake before the prehistoric bridge at the Seedamm isthmus was re-built in 1358. In 1798 the Helvetic Republic secularized the Einsiedeln Abbey's property, and Ufenau was given to the non-durable Canton of Linth. In 1805 Ufenau was given by the merchant Family Curti from Rapperswil to the Einsiedeln Abbey. 
5800 Vitis vinifera Blauburgunder (Pinot noir) were planted in 1986. The Einsiedeln Abbey owns 1 hectare (2.5 acres) of the Ufenau vineyards which are cultivated by its winery.
On 7 December 2003 the Ufenau association was founded, one year later «Freunde der Insel Ufnau». Friends of Ufenau island is a booster club to finance some projects for maintenance of the buildings located on the island, including both churches, and for the restaurant's renewal. It supports a long-time idea called «Insel der Stille» (island of silence), including a path way for disabled people around the island (completed in 2007), and regeneration of the island's shore areas to prevent increased erosion.
Ufenau