Michael Werner Sagmeister was born July 27, 1959, in Frankfurt am Main, West Germany. Raised largely by his grandparents, he taught himself guitar rather than coming up through formal lessons. In 1975 he was already playing in a band with Christoph Oeser and Bernd Kohn in what he later described as the boundary area between rock jazz and blues, and in 1978 he formed the Michael Sagmeister Trio with bassist Udo Kistner and drummer Michael Küttner. The trio was singled out as a "newcomer" act at that year's Frankfurt Jazz Festival, and guitarist Volker Kriegel, a founding member of the United Jazz and Rock Ensemble, produced the group's self-titled debut for Mood Records in 1978, followed by a second trio album, Ganshy, in 1980.

Through the early 1980s Sagmeister built a run of leader albums for Mood Records: The Silent Spectacle (1982), recorded with saxophonist Christof Lauer; Waiting for Better Days (1983); Two Is a Crowd (1984), featuring bassist Thomas Heidepriem; and Looking Out My Window (1987). A supporting-act tour with the United Jazz and Rock Ensemble in the early 1980s widened his audience considerably, and German critics began calling him a jazz-guitar wunderkind for a technique built on hard-bop foundations, with Pat Martino and Wes Montgomery cited as his earliest models.

The following decade brought both new duo partnerships and a move into music education. Sagmeister recorded So Near So Far (1987) and later Binary (1999) with pianist Christoph Spendel, having already appeared as a sideman on Spendel's own albums Limousine (1980) and Between the Moments (1984). He released A Certain Gift - Live (1990) and Still with Me (1992) on MGI Records, then Motions and Emotions (1993) and Soulful Questions (1995) on Bell Records. From 1993 to 1997 he was a lecturer at Berklee College of Music in Boston, and in 1999 he was appointed a tenured professor at the Hochschule für Musik und Darstellende Kunst (HfMDK) in Frankfurt, a post he continues to hold. His recording home shifted around the same time to Acoustic Music Records, beginning with Here and Now (1998).

The 2000s produced some of the most personally significant recordings of his career, starting with Conversation (2000), a full studio collaboration with Pat Martino, one of the guitarists who had shaped his playing since adolescence. He followed it with Dualism (2002), a duo album with vibraphonist Dave Samuels, and Dedicato - Canzoni E Jazz (2000), recorded with Italian singer-songwriter Camillo D'Ancona. Across the same period he built an extended partnership with vocalist Britta Medeiros, recording three albums together: The Way We Feel About It (2003), When the Moment Sings (2005), and Soul Ticket (2006). Alongside his performing and teaching work, Sagmeister has written three instructional guitar books, including Michael Sagmeister's Jazzgitarre, regarded as a standard text in German jazz-guitar pedagogy.

He continued recording steadily into the 2010s and beyond: True to the Moment (2010); Nell'Anima (2012), a collaboration with Italian singer Antonella D'Orio, who later became his wife; and Home (2015). In 2019 he received the Hessischer Jazzpreis (Hessian Jazz Prize), with the jury describing him as among the most significant German fusion guitarists while stressing that the label alone undersells the jazz improvisational grounding running through his current solo and duo work. He dedicated The Antonella Letters (2020) to his wife, and has continued releasing new material since, including Story Board (2021) and Opposites Attract (2024), a collaboration with guitarist Werner Eismann. Over a career spanning nearly five decades he has also performed alongside internationally recognized jazz figures including Billy Cobham, Jack DeJohnette, Randy Brecker, and Miroslav Vitouš.

Sagmeister's playing grew out of hard bop, with Pat Martino and Wes Montgomery as his formative models, and it carried him into jazz fusion as his main idiom by the 1980s, when he was praised in the German press as a technical prodigy on the instrument. His later work leans further into blues-inflected, neo-bop phrasing without losing the fusion vocabulary that defined his early records. He has built much of his mature career around the duo format, a setting in which, according to his own label's promotional writing, he can range across a wide palette of tone and color as both soloist and accompanist; his long-running duo recordings with pianist Christoph Spendel and vocalist Britta Medeiros, and later with his wife Antonella D'Orio, all showcase that side of his playing. His parallel career as an educator, first at Berklee and since 1999 as a tenured professor at Frankfurt's HfMDK, together with three published instructional books, has made him one of the more influential jazz-guitar teachers of his generation in Germany.