Ferenc Speth began his sculptural activity in Pécs concurrently with the investment of Zsigmond Berényi, Bishop of Pécs (1740-48). It cannot be excluded that the appearance of the master in Pécs stemmed from the beshop's earlier artistic connections. Speth was first mentioned in the sources in 1741, when he was commissioned by Canon József Givovics with the decorative elements of a marble altar in Pécs Cathedral's Chapel of St. Emeric. He also carved the portal decorations of the chapel (1743). The restoration of the angle heads of the Szathmáry tabernacle, defaced by the Turks, can be attributed to him, as well as the carving of the coat of arms on the Berényi Fountain near the Cathedral (1748).

His workshop also received several commissions from the Bishop György Klimó (1751-1777). His last work as a stone-carver was the restoration of the Hampo coat of arms above the portal of the Episcopal Palace in Pécs (1754). As a wood-carver, he made the richly carved Rococo sacristy wardrobes of Pécs Cathedral together with the local carpenter András Polacsek (1758), and the canons' stalls with the carpenter József Schwerer (1762). The models of the latter were the stalls in the choir of Pozsony Cathedral, made by workshop of Georg Raphael Donner. Between 1758 and 1777 he completed the furnishing of the sacristy with eight kneelers with inserted paintings and Rococo ends. In 1765 he made pews with rich ornamental carvings and angel heads in the row before the stalls, after the pews of Vienna's Peterskirche.

Ferenc Speth and his workshop worked some thirty-eight years in the service of Pécs Cathedral and Diocese. In 1770 the Pécs Chapter already contracted for new pews with his widow.