|Successor||Emiel Jan Seghers|
|Other posts||Superior of the St. Joseph Minor Seminary|
|Ordination||20 September 1856|
|Consecration||27 January 1890|
|Motto||Vivat Jesus !|
|Coat of arms|
Stillemans began studies at the St. Joseph Minor Seminary of Sint-Niklaas in 1846. In 1853 he studied at the major seminary in Ghent. in 1860 he earned a doctoral degree in philosophy at Leuven. Stillemans' brother, Pierre-Louis Stillemans, also became a priest.
He was named in 1867 Superior of the St. Joseph Minor Seminary of Sint-Niklaas, for a period of 21 years. He became president of the Major seminary in 1888 and canon of the cathedral chapter of Ghent and member of the episcopal council. He was canon elect after the sudden death of Henri-Charles Lambrecht. He promoted the Gothic Revival, and had the current Episcopal Palace in Ghent restyled as well he constructed the new major seminary in Ghent.
He named his brother priest Pierre-Louis Stillemans Honorary canon of St-Bavon.
During his episcopate he suspended in 1899 under pression of the royal court and Minister Woeste the political priest in Aalst, Adolf Daens. He promoted the social cultural movement of Flanders. In 1902 he consecrated the Abbey church of Dendermonde. In 1906, he celebrated his golden jubilee of priest and in 1914, his silver jubilee of bishop of Ghent. He was honored with the sacred pallium with papal permission at the end of his career. A street was named in his honor in Sint-Niklaas, as well a colored window inside the town hall, he gifted Sint-Niklaas with a large copy of his portrait. The colors of the city, blue and yellow are reflected in his heraldic episcopal crest.