Simon Phillips was born in London on February 6, 1957, the son of Sid Phillips, a British jazz clarinetist, bandleader and arranger. He began playing professionally at twelve in a Dixieland band led by his father and stayed with it for four years. Sid Phillips passed away in May 1973, when his son was sixteen. Two Generations, a 1972 album credited to Sid Phillips and His Band and The Simon Sound, is his earliest credited release. After his father's death he moved into pop and rock, found work in a London production of Jesus Christ Superstar, and picked up session work from members of the cast, which led to more.

Most of what he recorded over the next two decades was rock and pop, and this profile says so openly because that is the larger part of his catalogue. In 1976 he drummed on 801 Live, the Phil Manzanera and Brian Eno live album. In 1977 he took the drum chair for Judas Priest's Sin After Sin, where his double bass drum playing is often cited as an early model for later heavy metal, and he played on Jack Bruce's How's Tricks. In 1979 he is on L. Shankar's Touch Me There, produced by Frank Zappa. In 1980 he played on Jeff Beck's There & Back, on the Michael Schenker Group's debut, on Mike Rutherford's Smallcreep's Day and on Pete Townshend's Empty Glass, and he drummed and played percussion on Stanley Clarke's Rocks, Pebbles and Sand. He went on to play on four Mike Oldfield albums between 1983 and 1991, and he was the drummer on the Who's 1989 American reunion tour.

The jazz-fusion thread runs through all of it. In 1982 he formed RMS with the guitarist Ray Russell and the bassist Mo Foster, a trio of London session players who worked in jazz fusion. At the Montreux Jazz Festival in 1983 they played with the arranger Gil Evans as special guest, a set later issued on DVD, and a 1990 release credited to Gil Evans with RMS, Take Me to the Sun, has Phillips on drums for three of its four tracks. His first record under his own name, Protocol (1989), he made alone, playing every instrument. He moved to Los Angeles in the early 1990s and is based there.

In 1992 Toto, whose drummer Jeff Porcaro had died that August, invited him to fill in. He joined the band after the tour for Kingdom of Desire, drummed on Steve Lukather's solo album Candyman (1994), and made his first Toto studio album with Tambu (1995). He stayed through Mindfields (1999), Through the Looking Glass (2002) and Falling in Between (2006), played his last Toto show in 2013 and left in 2014 to concentrate on his own projects. Keith Carlock took the chair. Toto is the work he is best known for with a general audience, and it is a pop-rock band, not a jazz one.

His own records have been mostly jazz fusion. Symbiosis (1995), Another Lifetime (1997) and the live Out of the Blue (1999) came out on Lipstick Records, with players including Ray Russell, Mitchel Forman, Anthony Jackson and Andy Timmons. He led a band at the North Sea Jazz Festival in 1997. Vantage Point (2000, Jazzline), co-credited to the pianist Jeff Babko, is the most acoustic of them: a quintet with the trumpeter Walt Fowler, the saxophonist Brandon Fields and the bassist Dave Carpenter, closing with a piece titled "Spirits of Trane." In 2009 he formed the instrumental trio PSP with the keyboardist Philippe Saisse and the bassist Pino Palladino, which toured Europe in 2009 and 2010, and in 2011 he was the drummer on 21 Spices, the percussionist Trilok Gurtu's album with the NDR Bigband.

From 2011 to 2016 he was the drummer in Hiromi Uehara's Trio Project with the bassist Anthony Jackson. The group made four albums for Telarc, Voice (2011), Move (2012), Alive (2014) and Spark (2016). Move and Alive reached the top ten of Billboard's jazz albums chart, and Spark reached number one. Alongside that he rebuilt his own band as Protocol, with Ernest Tibbs on bass and a changing front line. Protocol II (2013) won the jazz instrumental album category at the 14th Independent Music Awards in 2015. Protocol 4 (2017, with the guitarist Greg Howe) was nominated for the Grammy for Best Contemporary Instrumental Album at the 61st Grammy Awards. Protocol V followed in 2022 and Protocol 6 in 2026. He was inducted into the Modern Drummer Hall of Fame in 2003.

He remains active. As of November 3, 2026, his official site lists European Protocol concerts starting on November 4 in Bielsko-Biala, Poland, with dates in Berlin and Heinsberg, Germany, on the next two days. Hiromi's site announced on October 29, 2026 that the Trio Project will play fourteen shows at Blue Note Tokyo from December 28, 2026 to January 3, 2027, with Phillips on drums again and James Genus on bass in place of Anthony Jackson, who passed away in 2025.

Phillips is a technical, high-volume drummer, associated with a large kit and double bass drum work, and he is unusually involved in how drums are recorded: he engineers, mixes and produces his own records and has co-produced albums by Mike Oldfield, Derek Sherinian, Planet X and Toto. He names Buddy Rich, Grady Tate, Louie Bellson, Tony Williams, Billy Cobham, Steve Gadd, Ian Paice, Tommy Aldridge and Bernard Purdie as his main influences, a list that puts big-band swing, jazz-fusion and hard-rock drumming side by side, which is also a fair description of his career.

Reference works sort him by which of his two careers they are describing. English Wikipedia calls him a jazz-fusion and rock drummer, and AllMusic's style tags for him include fusion, jazz-rock and post-bop. Modern Drummer readers voted him number one in its fusion category in 2019. His own records are electric and composed, built around band writing and groove, with Vantage Point as the acoustic exception; this is not bebop or swing drumming, and most of the rest of his catalogue is rock and pop.