Hailing from a genuine Rapid Wien family, he is the younger brother of former Rapid Wien player Wolfgang Kienast and uncle of current Austria international Roman Kienast.
[1] A versatile player, Kienast played predominantly in midfield for Rapid, but was also employed in defence or in attack.
After his 14 seasons at Rapid, he moved to city rivals Favoritner AC.
He finished his career with minor sides Süßenbrunn and SG FavAC Simmering.
He played a major part in the most successful of Rapid teams in the 1980s, claiming the League crown four times and most prominently losing the UEFA Cup Winners Cup Final in 1985 against Everton.