Michael King grew up in Chicago and came to the keyboard the long way round. He started on drums in his local church band at four years old, and it was that rhythmic apprenticeship, by his own account, that pulled him toward the piano and the organ, which he began playing by ear at fourteen. He went to Lincoln Park High School on the city's North Side, won merit scholarships to the Ravinia Jazz Scholars program and to the Thelonious Monk Institute, and then took his conservatory training at Oberlin. He also studied privately with Willie Pickens, the Chicago pianist who taught most of the city's younger players; the vocalist Milton Suggs, whose godfather Pickens was, describes King in his own liner text as a fellow Chicago native and a fellow Pickens student.

New York came next, and the club record starts early. The SmallsLIVE archive puts him at a Smalls after-hours jam session on January 23, 2013, and tracks roughly seventy-five sets at Smalls, Mezzrow and Jazzcultural over the thirteen years since, spread across two artist accounts under the two forms of his name. The longest-running of those associations is trombonist Corey Wallace's DUBtet, eleven listings between December 2015 and May 2026. Along the way the archive names Wayne Escoffery's quartet, David Gibson's quartet, Joe Dyson, Sasha Berliner, Donald Edwards, Stacy Dillard, E.J. Strickland, Nicole Glover, Noam Wiesenberg, Lucas Pino's nonet, Adi Meyerson, Joel Ross and Kassa Overall, and it also documents his own trio, which played two nights at Mezzrow on August 29 and 30, 2025 and appeared in Trinity Church's Jazz at One series on October 6, 2025.

Two of his earliest recorded relationships trace straight back to Oberlin. Robin Eubanks taught jazz trombone and jazz composition there for two decades, and King turns up in both of the bands Eubanks was recording in the mid-2010s: the electric group Mental Images, on Klassik Rock Vol. 1 (ArtistShare, 2014), where he holds the piano and keyboard chair on six of the nine pieces alongside Kris Bowers, and the sixteen-piece Mass Line Big Band on More Than Meets The Ear (ArtistShare, 2015), where he plays organ next to Glenn Zaleski on piano, in a horn section that ran from Lew Soloff and Duane Eubanks to Antonio Hart and Marcus Strickland. That album's own credits acknowledge support from Oberlin College research status.

The association that has defined his recorded career is with trumpeter Theo Croker, and it now runs to four albums over six years. He is on Escape Velocity (2016), fourteen of its fifteen tracks, playing Rhodes, Hammond C2, Minimoog, Moog Voyager, Prophet '08 and congas as well as piano; on Star People Nation (2019), eight of ten; on BLK2Life || A Future Past (2021), eleven of thirteen, where he also arranges the closing "Pathways"; and on Love Quantum (2022), nine of eleven, co-arranging "Love Thyself" with Croker. Around that spine sits a run of leader dates by musicians of roughly his own generation: Kassa Overall's Go Get Ice Cream And Listen To Jazz (2019) and I Think I'm Good (2020), where his contribution is synthesizers and Mellotron rather than piano; bassist Alexander Claffy's Claffy (2016) and Claffy II (2019); and Arto Lindsay's Cuidado Madame (2017), on which he plays organ throughout.

He is also a fixture of the Chicago diaspora on record. He plays piano on both of the albums saxophonist Isaiah Collier cut at Rudy Van Gelder's studio in Englewood Cliffs on September 23, 2020, Cosmic Transitions (2021) and the two-piece Lift Every Voice (2022), and he holds the piano chair in the working quintet on Marquis Hill's Composers Collective: Beyond The Jukebox (2024), with Joel Ross on vibraphone, Junius Paul on bass and Corey Fonville on drums. In the mid-2010s he was the keyboard player in Soul Understated, the Mavis "Swan" Poole and Jeremy Clemons band, whose Swanbean Quintet took him into Smalls repeatedly between 2014 and 2016. Since 2025 he has appeared on three vocal albums in a row: China Moses's It's Complicated..., Theo Bleckmann's Love And Anger on Sunnyside, and Ledisi's Dinah Washington tribute For Dinah, produced by Christian McBride for Candid, where King plays piano on five of the eight tracks. The McBride connection is not a one-off session: King holds the piano chair in Ursa Major, the bassist's working band, alongside Nicole Glover on tenor saxophone, Ely Perlman on guitar and Savannah Harris on drums. The band has barely recorded so far, its only issued item being the 7-inch single "More Is" / "Smo" on Mack Avenue in March 2025, which is why the credit is invisible on his Discogs artist page and why it does not appear in the touring list on his own site either.

The record billed under his own name so far is a duo. Pure Intention (Imani Records, July 12, 2024), credited "Milton Suggs With Michael King," is thirteen pieces for voice and piano only, cut in a single day at Samurai Hotel Recording Studio in Queens on December 18, 2023: Horace Silver, Cedar Walton, Lee Morgan, Benny Golson, Buster Williams, Larry Willis, Mulgrew Miller and Kenny Garrett tunes given lyrics by Suggs, plus Gamble and Huff's "Cry Together" and Frankie Beverly's "Golden Time Of Day." Suggs credits King's harmonic reworking with opening up arrangements he had not previously imagined. The two had been playing together for years before it: SmallsLIVE lists a Suggs, King and Dezron Douglas night at Mezzrow on September 21, 2022. King's own listing of his current touring work names his trio, Dee Dee Bridgewater, Robin Eubanks, Marquis Hill, Theo Croker, Soul Understated, Melissa Aldana and Marcus Printup, and he names Bobby Watson, Kevin Eubanks, David Liebman, Gary Bartz, Billy Hart, Joel Frahm, Rufus Reid and Antonio Hart among the players he has worked with.

King is that increasingly common but still unusual thing, an acoustic pianist with a conservatory technique who is equally employable as a synthesist, and the two halves of him are audible on the same records. On Croker's albums the credits read like a keyboard inventory (Fender Rhodes, Hammond C2 and B3, Minimoog, Moog Voyager, Prophet '08, Prophet Pro 2, Mellotron) and on Isaiah Collier's Van Gelder date he plays nothing but acoustic piano in a Coltrane-lineage quartet. The church organ from his childhood is still doing work in both directions: it is the reason a straight-ahead bassist's date like Claffy hires him for organ and electric piano rather than piano, and it is part of why Ledisi's producers put him on a Dinah Washington programme. The clearest description of his playing in print is Guillaume Lagrée's review of Itamar Borochov's Boomerang for Citizen Jazz, which singles out the piano ostinato under the opening theme and praises him for risking stride accents over odd-numbered pulses and for pouring out voicings and block chords. That combination, an old-fashioned rhythmic attack applied to non-Western meters and to electric textures, is a fair summary of what leaders as unlike Robin Eubanks, Kassa Overall, Isaiah Collier and Milton Suggs are all hiring. His stated lineage runs through Willie Pickens in Chicago and the Oberlin jazz faculty, and his first instrument, drums in a church band from the age of four, is the thing he himself credits for the rest.