Alongside the titled positions referenced above, Inkinen works at the highest level as a guest conductor with orchestras including the Munich Philharmonic, La Scala Philharmonic, Los Angeles Philharmonic, Rotterdam Philharmonic and Israel Philharmonic Orchestras, the Deutsche Symphony Orchestra Berlin, WDR Symphony Orchestra Cologne, Bavarian Radio Symphony, Bamberg Symphony, Vienna Radio Symphony and BBC Symphony Orchestras, Staatskapelle Dresden, the Leipzig Gewandhaus, Maggio Musicale, the National Symphony Orchestra Washington, CBSO and Orchestre Philharmonique de Radio France. Inkinen also enjoys successful collaborations with soloists such as Vadim Repin, Hilary Hahn, Pinchas Zukerman, Nikolaj Znaider, Jean Yves Thibaudet, Alexander Toradze and Elisabeth Leonskaja.
In September 2013, Inkinen was taken on at relatively short notice to conduct Opera Australia's first ever production of Wagner's Der Ring des Nibelungen, directed by Neil Armfield. This, the third ever Ring Cycle in Australia's history has been met with the highest acclamation from the international press and described as "...theatrically enthralling, conceptually provoking, and visually gorgeous..." (Sydney Morning Herald). In August 2014, Australia's Helpmann Awards voted Inkinen as Best Music Direction for Opera Australia's Ring Cycle, recognising artistic excellence throughout Australia's vibrant performing arts scene.
In the operatic pit, he has conducted at the Finnish National Opera and made a very successful debut at La Monnaie in Brussels conducting the Rite of Spring with the Pina Bausch Dance Company. In spring 2012 he made debuts at the Staatsoper Berlin and Bayerische Staatsoper Munich conducting Eugene Onegin and in 2013 he conducted performances of Wagner's Walkure and Das Rheingold in Palermo's Teatro Massimo. Inkinen was consequently awarded Italy's National Association of Music Critics with the Franco Abbiati Prize for "Best Show" for Das Rheingold. The 2014 - 2015 season sees his return to the Finnish National Opera conducting Sibelius' Kullervo and Stravinsky's Rite of Spring in a debut with Cologne Opera in a choreography by Sasha Waltz.
Inkinen is also an accomplished violinist and studied at the Cologne Music Academy with Zakhar Bron. He has appeared as soloist with many of the leading Finnish Orchestras including Finnish Radio Symphony, Helsinki Philharmonic with whom he performed the Sibelius Concerto in a concert that celebrated the 100th anniversary of their performance of the work and has play/directed orchestras including Teatro Carlo Felice Genova, RAI Torino, Norrkopings Symphony and Orchestre National de Lyon.