Recent highlights include his debut performance at New York's Carnegie Hall, leading the Greek Youth Symphony Orchestra, and a highly acclaimed, last-minute jump-in to conduct the London Philharmonic Orchestra in Brahms 4 at the Megaron, when Cannelakis was taken ill at the very last-minute.
Grammenos has conducted the Houston Symphony Orchestra, Belgian National Orchestra, Orchestre Symphonique de Québec, and Cameristi della Scala, collaborating with distinguished soloists such as Khatia Buniatishvili and Renaud Capuçon. In the coming months, he is set to make his first recording with the Philharmonia Orchestra in London.
On the opera stage, Grammenos has conducted Puccini La Bohème with New Zealand Opera and English Touring Opera and Rossini La Cenerentola with the Royal Northern Sinfonia at Nevill Holt Opera.
As Artistic Director of the Greek Youth Symphony Orchestra, he regularly performs at the Megaron in Athens and has led the orchestra in performances at prestigious venues including Berlin’s Konzerthaus (twice), and Amsterdam's Concertgebouw. In December 2025, the orchestra will perform with acclaimed soloist Leonidas Kavakos under Grammenos's direction.