Salminen is distinguished by an imposing figure and height (6' 5"); a cavernous, heavy, dark voice with a huge upper register; and an expressive face. According to one reviewer, in his prime Salminen was "... simply the largest bass voice in captivity. It is not just its roar in powering over Wagner's maximum orchestra, but the way he carves the sonority and forms the color."
Salminen has a special gift for playing menacing, threatening characters. He performed as Fafner and Hagen in the PBS video broadcast Ring Cycle from the Metropolitan Opera, for the largest viewing-audience of the Ring in history.
Salminen has a contract at the Zurich Opera, and he also frequently performs in his native Finland.
At the Bayreuth Festival he first appeared in 1976 as Titurel (Parsifal), and as Hunding (Die Walküre) and Fasolt (Das Rheingold) in the Jahrhundertring (Centenary Ring) in 1976, celebrating the centenary of both the festival and the first performance of the complete cycle, conducted by Pierre Boulez and staged by Patrice Chéreau, recorded and filmed in 1979 and 1980. He continued until 1989 adding Fafner (Rheingold, Siegfried), Daland (Der fliegende Holländer), King Marke (Tristan und Isolde), Heinrich (Lohengrin), Pogner (Meistersinger), Landgraf (Tannhäuser) and Hagen (Götterdämmerung) to his roles there. He made his Metropolitan Opera debut as King Marke on January 9th, 1981, and performed 132 times there in several roles, until March 28, 2008.
Other important roles are King Philip II (Don Carlos by Giuseppe Verdi), the Grand Inquisitor in the same work, Seneca in L'Incoronazione di Poppea, Sarastro in Die Zauberflöte, the Commendatore in Don Giovanni, the title role in Boris Godunov and Prince Ivan Khovansky in Khovanshchina. He also performs in sacred music and concert recitals.
Salminen is a widely video-taped singing actor with three different performances as Hagen available on DVD; also two performances as the Commendatore, several as Sarastro, two as Hunding and two as Daland. Videotaped performances and films are also available as King Phillip II, the Grand Inquisitor, Seneca, Gurnemanz, Pogner, Kaspar, Rasputin (in the Finnish opera by composer Einojuhani Rautavaara), and Boris Godunov.
In his youth he earned money for voice lessons by singing Finnish tangos in night clubs. He has published an anthology of Finnish tangos. He first caught public eye as a lucky understudy in the role of King Philip II, when he was just 24 years old. He continues performing this role and a DVD was released in 2014.