In 1607 the mill, which is placed on the base of Rosenburg am Kamp, is documentary mentioned the first time. On December 30th 1607 Erasmus Herr von Lichtenstein zu Corneidt left Stift Altenburg the Schulhofmühle in his will. The Mantler family acquires the house #12 at Rosenburg including the associated mill building with five grinding stones in 1853.

In the 19th century the mill got independent from immediate hydroelectricity. It increased its capacity first through steam engines and then through purchased electricity from the national grid. The expansion of the Mantler-Mühle started at the end of the 19th century.

In 1925 a serious fire destroyed the mill. In the very same year a new construction was built according to modern aspects.

After World War II the factory was brought two times to state-of-the-art. In 1973 the Hohenbichler mill which is 5km away was leased. In 1982 it was purchased. In 1975 there was erected a newly Zweibodenmühle in Rosenburg. In 1982 the new construction of a rye mill took place in Gars and in 1984 it was brought on line. In 1984 it was erected a hulling mill there to hull sunflower seeds and spelt. In Rosenburg and in Gars there exist facilities to process soy for human sustentation. In 1997 the roller mills of the wheat mill were reconditioned. In 1952 and 1968 there were built new elevators with a capacity of 6 300t.

The wheat mill in Rosenburg and the rye mill in Gars are computer-operated so that the grinding operation happens without employees. The performance of the wheat mill amounts 90t in 24h and off the rye mill 30t in 24h.

In 1966 it was started with the manufacturing of ready-made flour under the trade mark of Komplet and after compositions of the company Komplet Abel und Schärfer Germany. Ready-made flours are premixes of flour, sugar, starch, backery improver, shreds, etc. so that the baker only has to add water and yeast for the production of diverse types of bread and pastries.

After the fall of the iron curtain in 1990 there were founded subsidiary companies in Hungary, Slovenia, Slovakia and the Czech Republic.

In 1995 the sales and distribution was outsourced into the newly founded company Komplet Mantler G.m.b.H. & Co KG. Half of the company is owned by Mantler-Mühle Rosenburg Kom. Ges. and the other half by the company Abel und Schäfer Deutschland so that we could assure the worldwide distribution of the Komplet-products and the access to the newest developments in the nutrition science field. Today the Komplet-products can be bought in Europe and all over the world, particularly in the United States of America. The trade mark Komplet has a 30% market share in Austria.

Since the late 1980s the Mantler-Mühle occupies oneself with food intolerances and developed a gluten-free flour mixture. At first it was sold only in direct sale and through G&M Pharma but since 2002 it is also available in grocery stores.

In May 2008 a completely new facility for the production of gluten-free mixtures is built in Rosenburg.

Since autumn 2009 there is a new gluten-free brown-bread mixture onto the market. This mixture was developed especially for the production of rustic brown breads.