He wrote or co-wrote much of Toto's original material, including the band's three most popular songs: "Hold the Line", "Rosanna", and "Africa".

In addition, Paich has worked as a songwriter, session musician, and producer with a host of artists including Helen Reddy, Boz Scaggs, and Michael Jackson.

[1] A prolific writer of chart-performing songs (13 Top 40 hits on the Billboard Hot 100), Paich wrote or co-wrote such tracks as "Hold the Line", "99", "Lowdown", "Lido Shuffle", "Georgy Porgy", "Rosanna", "Hydra", "Holyanna", "Pamela", "Got To Be Real", "Lady Love Me (One More Time)", and "Miss Sun".

In 2010, Paich resumed performing with Toto, and until mid-2018 was one of the band's keyboard players, alongside fellow original member Steve Porcaro.

Guitarist Steve Lukather later stated that Paich's absence stemmed partially from an apparent seizure he suffered on the bus during the band's early 2018 European tour.

[2] Paich returned to the stage with Toto for the opening and closing shows of their 2019 US tour, reportedly their last, on September 20 in Los Angeles and October 20 in Philadelphia.

As songwriter he wrote or co-wrote songs for Cher,[7][8] The Jacksons,[9] Andy Williams,[10] George Benson,[11] Glen Campbell,[12] Boz Scaggs,[13] Jon Anderson[14] (Yes), Cherie & Marie Currie,[15][16] and Chicago.

[17] As arranger he worked for Michael Jackson, Rod Stewart, Patti Austin, Donna Summer, the Doobie Brothers, Sheryl Crow and many more.

1 R&B hit "Break It to Me Gently" by Aretha Franklin.In the early and mid-1980s, Paich often worked with well-known producers Quincy Jones and David Foster.

As a session musician, Paich has played on numerous soundtracks and on albums by many artists, including Elkie Brooks' album Rich Man's Woman; Bryan Adams' song "Please Forgive Me"; the Michael Jackson songs "Earth Song", "The Girl Is Mine", "Heal the World", "Stranger in Moscow", and "I Just Can't Stop Loving You"; and the USA for Africa song "We Are the World", as well as work with Aretha Franklin, Boz Scaggs, Quincy Jones, Melanie Safka, Don Henley, Diana Ross, the Doobie Brothers, Neil Diamond, Seals and Crofts, Steely Dan, Elton John, Joe Cocker, Rod Stewart, Cher, Sarah Vaughan, Randy Newman, Tina Turner, the Brothers Johnson and Pink.