In June 2010, Marini Jr. was named artistic director at the first Brianza Blues Festival, in Villa Reale (Monza, Italy).

He played on Frank Zappa's 1977 album Zappa in New York, on Cindy Bullens' 1978 album Desire Wire, and has worked with Aerosmith, Deodato, Maureen McGovern, Steely Dan, James Taylor, Dionne Warwick, the Buddy Rich Big Band, and the Woody Herman Orchestra.

The liner notes[2] of the album were written by Grammy Award-winning composer, arranger, and producer Bob Belden.

Marini's work as an arranger and composer has been influenced by Gil Evans, Bob Brookmeyer, Thad Jones, and Don Ellis, as well as rock, pop, and avant-garde music.

For example, his song, "Hip Pickles," written for Blood, Sweat and Tears, is described by reviewer Jack Bowers[3] of AllAboutJazz.com, as follows: "Marini's unorthodox notions surface on 'Hip Pickles,' whose free' intro gives way to a melody played by screaming trumpets and Clapton-like guitar, prefacing a stormy interchange between Marini (alto) and Tom Wolfe [on guitar].