In 1960 he graduated from the Leningrad State Theatre Institute named after A. N. Ostrovsky (acting class of Professor Boris Petrov). He was invited to the Petrozavodsk Music and Drama Theater, where he played 13 roles in the classical and modern repertoire: lyrical comedies, psychological dramas, ballets, operettas. He worked a lot at Petrozavodsk television studio and radio. At the same time, in 1960, he made his film debut: the young actor played one of the main roles - a cheerful village boy Glory - in the film by Joseph Heifetz Horizon.
In 1962, Geliy Sysoev joined the troupe of the Leningrad State Academic Drama Theater named after A.S. Pushkin, where he worked until 1972, playing many different roles in 40 performances. In the first performance – “Friends and Years” by L. Zorin (1962) – Sysoev performed two roles at once: a young dashing womanizer Igor and a wise old buffetman, showing a tendency to sharp stage drawing, bright character. Among the roles played by Helii Sysoyev during this decade, it is worth noting such as Aleshka (“On the Bottom” by M. Gorky, 1968), philistine Shapkin (“Thunderstorm” by A. Ostrovsky, 1963), Sevka (“Honor your father” by V. Lavrentiev, 1965), Igor (“On the wild shore” by B. Polevoy 1964), Belogubov (“Profit place” by A. Ostrovsky, 1968), Pilot (“Night in Belovodsk” by L. Obukhova, 1964), Sashabushka (1967), “Darbushka” by Yulebushka, 1967). In one of the reviews of those years, it is rightly noted: “It is striking the ability of an actor in every small role to show a great character, a whole biography.”
All this time, Geliy Sysoev is actively starring in films, he is invited to the role of only entering the life of charming young heroes: Andreika “Wedding in Malinovka”, Volodka-Chaldon “Today a new attraction”, secular frivolous magazine “Green carriage” and others. As an actor of the Alexandrinsky Theatre, Geliy Sysoev successfully made his debut on the stage of the Musical Comedy Theatre, playing the main role - a storyteller - in the lyrical comedy "Such a Night". In the Theater of Musical Comedy Heliy Sysoev also played Count Boni in the operetta “Queen of Chardash” – the role brought the actor a huge audience success. From 1972 to 1989, Geliy Sysoev worked in the studio of the actor at Lenfilm.
The actor returned to the Alexandrinsky stage in 1989. Possession of many genres, musicality, the ability to paradoxically combine lyrics and eccentricities in roles, comic and deeply dramatic allowed the actor to immediately actively enter many performances. In his repertoire were as sharp roles - Tsar in "The Tale of Love" G. Gorbovitsky (1989), Sysa Psoich Rispolozhensky in the comedy A. Ostrovskiy "Our People - We Will Consider!" (director Vladimir Golubskiy, 1990), Fillurg in the comedy "Lysistrata" (director Vladimir Golubniets, 1990), "Seker in the field" Vladimir Golubniyevskiy, 1991), "Grezhierkiyevskiy in the film "Alextrazhinskiy", "Alextsa", "Alexerya" (1990), "Alextrazhy V. One of the significant stage works of Heliya Sysoyev was the role of the great Swedish writer August Strindberg in the play Who is Stronger? (1997), consisting of three one-act plays by contemporary Swedish playwrights P.-U. Enquist, E. Sverling and Strindberg himself. The actor delicately and subtly approached the image of the great Swedish writer. Not striving for an exact external similarity with the prototype, the actor tries to convey the personal volume of his hero, emphasizing the paradox of the artist’s internal relations with the world. In the performance of Heliy Sysoyev, Strindberg appears as a man whose complex inner world is full of painful spiritual contradictions, doubts and, at the same time, a thirst for a breakthrough to harmony and light.