The designer proved capable of creatively using folk art, especially Polish folk art, in the theatre. He discovered the value of wooden sculptures, paintings on glass and wicker objects. Inspired by folk, primitive and plebeian art, he also began using joyous, bright colors. Kilian said that even if he were to design Macbeth, he would show its cruel criminality in bright light, rather than hiding it in dark corners. In the productions Kilian designed, comedy mixed with farce and tragedy, whilst deliberate awkwardness, cheerfulness and frequent visual references blended to constitute a theatrical convention, creating a distance between viewers and the imagined stage world, a world that nevertheless remained thoroughly authentic.
The designer has a special admiration for the Polish creche, which he sees as nourishing the roots of Polish puppet theatre. The creche has often inspired his own designs.The artist explained:
The spirit of the creche, its artistic and logical division into the zones of hell, heaven and earth evokes monumental theatre, as paradoxical as that might sound. [...] The creche incorporates the essence of mystical theatre and all that inspired Romanticism and Neo-Romanticism, i.e. the possibility of mixing genres, metamorphosing reality into fantasy, transforming fantasy into the quotidian. All this is embodied in the creche and I find that fascinating. So much so that I consider the creche a symbol of Polish theatre.
Kilian got his first job with a dramatic theatre in 1959 when the famed Studencki Teatr Satyryków (Student Theatre of Satirists) invited him to work on a production. He created the settings for Wieża Malowana (The Painted Tower) directed by Jerzy Markuszewski, a one-man drama written and performed by Wojciech Siemion and composed of Polish folk poetry. In creating the settings, Kilian drew on his experiences in puppet theatre. An on otherwise empty stage, Siemion was surrounded by giant puppets resembling short, stocky women, which Kilian referred to as variations on Craig's 'uber-marionettes.'
In the 1960s Kilian also worked with Józef Gruda on several Polish classics at the Contemporary Theatre (Teatr Współczesny) in Szczecin, designing the scenery for Gruda's stagings of plays like Aleksander Fredro's Zemsta (The Revenge, 1960) and Damy i Huzary (Ladies and Hussars, 1962) and Stanisław Wyspiański's Wesele (The Wedding, 1963). He would get two more opportunities to design productions of the latter play. Both resulted from Kilian's collaboration with director Adam Hanuszkiewicz, initially at Warsaw's Popular Theatre (Teatr Powszechny) (1964) and later at the National Theatre (Teatr Narodowy) (1974). In the first of these stagings the scenery centered on a vast creche with characters riding out onto the stage on small platforms as figures might in a miniaturized nativity scene. For the second premiere the scenery derived directly from the author's stage directions describing a simple peasant hut.
Kilian also had multiple opportunities to design Wojciech Bogusławski's Krakovians and Highlanders, mounting productions of this play with director Bronisław Dąbrowski at the Słowacki Theatre (Teatr Słowackiego) in Kraków (1963) and with Jan Skotnicki at the Kochanowski Theatre (Teatr im. Jana Kochanowskiego) in Opole (1983). He also designed Ernest Bryll's Na szkle malowane (Painted on Glass) on more than once occasion, with Jan Skotnicki at the Silesian Operetta in Wrocław (1970) and at the New Theatre (Teatr Nowy) in Łódź (1970).
For Wojciech Bogusławski's sung play Lodoiska directed by Jan Kulczynski at Warsaw's Classical (Teatr Klasyczny) Theatre (1962), Kilian created folk-styled sets that resembled illustrations from children's books. Leon Schiller's Pastorałka (The Pastoral) is another play that has followed him throughout his life. He first designed a production under field conditions, i.e. in the Iraqi desert as a soldier of the Polish II Corps during World War II. He would go on to design scenery for eight different stagings of Schiller's work, including the productions directed by Jan Wilkowski at Warsaw's Popular Theatre (1964) and the Puppet Theatre in Białystok (1979), and that staged by Jarosław Kilian at the Polish Theatre (Teatr Polski) in Warsaw (1996).
Since the 1990s Adam Kilian has focused on designing scenery for productions directed by his son Jarosław. Within this duo, he produced plebeian and rural culture inspired scenery for Juliusz Słowacki's Balladyna at the Polish Theatre (Teatr Polski) in Szczecin (1991), as well as the sets for Shakespeare's Comedy of Errors at the Kochanowski Theatre in Opole (1991), and the same author's A Midsummer Night's Dream (1998) and The Tempest (2003) at the Polish Theatre in Warsaw. Working as a team, the Kilians also mounted Bolesław Leśmian's Przygody Sindbada Żeglarza (The Adventures of Sinbad the Sailor) at the Municipal Theatre (Teatr Miejski) in Gdynia (1992), staging the play once more in 2002 at the Polish Theatre in Warsaw, as well as Stanisław Grochowiak's Bestia i piekna (The Beast and Beauty) at the Puppet Theatre (Teatr Lalka) in Warsaw (1994). Most recently the duo revisited Balladyna, staging it in 2004 at Warsaw's Polish Theatre. Young designer Dorota Kołodyńska said of Adam Kilian: