Saarikoski's breakthrough was both critically and commercially Mitä tapahtuu todella? (What goes on really?) published in 1962. The collection of poems heralded a new era in Finnish culture, laying the foundation of Finnish "participating poetry", a style whose adherents insisted that poets should participate in politics through their work. Indeed, some of the poems featured in the collection do have a clear political tone, whereas in the 50's Finnish modernists were generally more inclined to think that art should be done solely for art's sake. Mitä tapahtuu todella? marked also a change in the poet's style. His early works Runoja (Poems) and Toisia Runoja (Other Poems), both published in 1958, are not yet "participating poetry" or "democratic poetry" as the poet himself called his style. Instead, they are distinguished by their references to Greek antiquity while the general style was modern, which has led literary critics to say that Saarikoski's first works form his "Greek period". Saarikoski's interest in Greek began very early on. In fact, he studied Greek and literature at the University of Helsinki in the 1950s, albeit he never received a degree.

During the 70's Saarikoski continued to publish poem collections. His admiration for the Greek philosopher Heraclitus deepened to such lengths that at one point Saarikoski adopted the philosopher's colloquial name "The Obscure", "Hämärä" in Finnish, to his poetry. Saarikoski began to obscure his poems intentionally and titled one of his collections Hämärän Tanssit (The Dark One's Dances, translated by Anselm Hollo), which is a reference to Heraclitus.

Saarikoski also wrote column by the pen-name "Nenä" ("Nose"). His columns satirized the church, the army, politics and, all in all, conservatism. In his columns, he parodied the official political jargon of his times in a very effective manner.

Saarikoski was a well-known celebrity in Finland due to his controversial personal life. He was an enthusiastic communist, was married four times and consumed alcohol heavily. Saarikoski himself said: "I make my life fiction so that it would be true". In an interview, Saarikoski's daughter, Helena Saarikoski, stated that her father was a prime example of a European bohemian, and as such helped to establish an image of a modern intellect in Finland.