Matthijs van der Moolen loves playing chamber music, both early and contemporary. He co-founded the Castello Consort. With this ensemble, they specialise in the expressive and virtuosic (chamber) music of the sixteenth and seventeenth century. They regularly perform in the foremost festivals and concert series all over Europe, and presented their debut CD ‘Fantastissimus’ in 2023. In 2025, Matthijs' solo album 'Ricercati' was released with the Navis Classics label. This EP contains early music by Virgiliano, and two premieres of new works for sackbut solo, that Martijn Padding wrote for him.

Matthijs is regularly teaching courses and workshops, including a bi-annual course on polychoral music for the Huismuziek organisation. Since 2024 he is also sackbut lecturer at the summer school 'Between Prague and Vienna' in Slavonice (Czechia).

As a researcher, Matthijs is currently working on his PhD on the trombone in seventeenth-century France, England, and the Low Countries. He is doing this at the Musikhochschule Freiburg (DE), in cooperation with the Schola Cantorum Basiliensis (CH). In 2024 he was selected for the REMArkable scheme, as one of the young researchers in early music that will be supported by the REMA organisation.

In concerts, Matthijs plays on a variety of instruments, ranging from original historical trombones from the 19^th century to accurate copies of earlier instruments. His most special instrument is the first exact copy of the only surviving renaissance trombone from Italy: the anonymous trombone that is part of the Accademia Filarmonica collection in Verona. Aron Vajna built this for him, using all the historical techniques. The instrument was made possible with the help of Stichting Eigen Muziekinstrument.

In 2018, Matthijs graduated cum laude from his studies of baroque trombone with Charles Toet at the Royal Conservatoire of The Hague, and specialised into renaissance music on trombone and slide trumpet even further with Catherine Motuz at the Schola Cantorum Basiliensis. He played with various ensembles, including Música Temprana, Bach Collegium Japan, Holland Baroque, Capriccio Stravagante, New Collegium, La Fonte Musica, Innsbrucker Hofmusik, Cappella Marciana (San Marco, Venice), Ghislieri Consort, and others.