Joseph Mehoffer was born in 1869 in Ropczyce. After his father, Wilhelm von Mehoffer, had moved to Krakow with the family, Mehoffer graduated from Kraków Academy of Fine Arts. In 1891 he received a scholarship and went to Paris, where he attended lectures at Ecole Nationale des Arts Decoratifis, Academie Julian, Akademie Colarossi, as well as lectures on the history of art at Ecole du Louvre. From 17 February 1892 until the end of 1893, he studied at Ecole Nationale de Beaux–Arts. During his studies he dealt with design art and easel painting.

The greatest fame came in 1895, when he won the competition for making the stained glass for St. Nicolas Gothic collegiate in Freiburg, Switzerland. His amazing work consisting of 21 glasses has remained there till this day. In 1900, during the World Exhibition, he won a gold medal for one of the Freiburg stained glasses entitled “Martyrs”.

After coming back to his home country, Mehoffer focused mostly on polychrome and stained glasses. Some of his crafts are: painting decorations for the Wawel Cathedral vault, polychromes and stained glasses in the chapel of Szafrańce and in the transept of the aforementioned cathedral. During the World Exhibition in St. Luis, he won a gold medal for his painting “Vocalist”, and a silver medal for his stained glass “Vita somnium breve”. His other stained glasses for Świętokrzyski chapel on Wawel were honoured during Grand Prix at the International Exhibition of Decorating Art in Paris.

The artist also realized his other projects in places such as: St. Mary's Basilica (Kościół Mariański) in Krakow, St. John’s Cathedral in Lwów, Morawy Abbey, the local church of St. Elizabeth in Jutrosin, St. Mary’s Cathedral in Włocławek, the Holly Heart of Jesus Christ’s Church in Turek, and the local church in Lubień.

He died on 7 July 1946 in Wadowice.