Although he had never received any formal training (in acting) he managed to earn a great respect of both filmmakers and audience members.

Practically at the beginning of his acting career, after a few minor films including Každý týždeň sedem dní (1964) and Nylonový mesiac (1965), he received the role of his lifetime in Marketa Lazarová (1966).

In interviews, he described with gratitude how the director František Vláčil completely changed his way of seeing the world during the long production of this movie.

Despite the impact the role had on the film (widely considered the best Czech cinema) and on his life, Velecký would probably be more recognized by Western audiences for his appearances in The Brothers Grimm (released 2005) and the Academy Award-nominated Želary (2003).

He was assistant director to Juraj Jakubisko on the film Zbehovia a pútnici (1968) and he applied his talent in fine arts during the 1990s.