Jeff Kashiwa was born in 1963 in Louisville, Kentucky, and moved with his family to the Seattle area as a young child. He grew up in Shoreline, Washington, and graduated from Shorecrest High School. His father, a jazz fan who liked Benny Goodman and Glenn Miller, gave him a clarinet, which he started on at about ten. Two years later he switched to the saxophone. AllMusic lists Chuck Mangione and Spyro Gyra among his early influences. His father passed away in 1992.

He studied at the Berklee College of Music in Boston from 1981 to 1983, where he took up straight-ahead jazz and won the second alto chair in Disney's All American College Band, then transferred to California State University, Long Beach and earned a Bachelor of Music in 1985. In Southern California he toured with the ska and reggae group the Untouchables, including a spot on MTV's first Spring Break broadcast, and for a time worked days at a grocery store while playing gigs at night.

The break came through a bassist. Kashiwa hired Steve Bailey, then playing with The Rippingtons, for a gig, and Bailey introduced him to the band's leader, the guitarist Russ Freeman. When the group's original saxophonist, Brandon Fields, left in 1989, Freeman hired Kashiwa. He stayed about a decade. The Rippingtons are a studio-built smooth jazz band on GRP and later Peak, and Kashiwa is one of the saxophone voices on that catalog. His own first two albums, Remember Catalina (1995) and Walk a Mile (1997), came out on Fahrenheit Records while he was still in the band.

In 1999 he left to concentrate on his own group, Coastal Access, with the bassist Melvin Davis, the guitarist Allen Hinds, the drummer Dave Hooper and the keyboardist Dave Kochanski, and Paul Taylor took the saxophone chair in the Rippingtons. Another Door Opens (Native Language Music, 2000) was produced by Brian Bromberg, Dave Kochanski and Kashiwa, with Jeff Lorber producing and co-writing one track, and its single "Hyde Park (The 'Ah, Oooh' Song)" was No. 1 on the Radio & Records airplay chart for more than eight weeks that year, according to AllMusic. Simple Truth (2002) and Peace of Mind (2004) followed on the same label, and Peace of Mind brought in Lorber, Russ Freeman, Dan Siegel and the saxophonists Kim Waters and Steve Cole. In those years he played sixty to eighty dates a year with Coastal Access, and AllMusic names Chuck Loeb as a frequent collaborator and co-producer.

In 2004 he approached other saxophonists about forming a group, which became The Sax Pack with Steve Cole and Kim Waters. Its three albums, The Sax Pack (2008), The Pack Is Back (2009) and Power of 3 (2015), all came out on Shanachie. He rejoined the Rippingtons for the group's 20th anniversary tour and album in 2006 and has returned for later records, including Modern Art (2009), which earned a Grammy nomination for Best Pop Instrumental Album at the 2010 ceremony, Côte d'Azur (2011) and Built to Last (2012). That nomination, credited to the band, is the only one listed under his name on the Recording Academy's site. His own albums stayed on Native Language Music for Play (2007), moved to Shanachie for Back in the Day (2009), and returned to Native Language Music for Let It Ride (2012), which features Chuck Loeb, Russ Freeman and David Benoit.

Fly Away (2017) added guest spots from the guitarist Marc Antoine, Miles Gilderdale of Acoustic Alchemy and Tom Schuman of Spyro Gyra. Sunrise (April 20, 2021) was released on his own, and Luminoso (June 25, 2024) is an album of Brazilian music built mostly from compositions by the singer-songwriter Joyce Moreno. He is based in Seattle and teaches music technology at Shoreline Community College; the college's advisory committee minutes for November 21, 2025 list him giving the department update. He is still active as of November 2026: touring dates with the guitarist Steve Oliver are listed for the year, including July 29 in Oakland and October 23 in White Rock, British Columbia, his single "Lift Me Up" came out on September 21, 2026, and he is a featured guest on "Lotus Flower," a single by Mario Rossi released September 18, 2026.

Kashiwa is a smooth jazz saxophonist in the radio sense of the term: melodic hooks, programmed or tightly sequenced rhythm sections, R&B and pop-leaning grooves, and songs built to sit on a playlist. A JazzUSA review of Another Door Opens said it follows the smooth jazz radio formula, with solid playing and pleasant songs, and picked out "Hyde Park" as the likely single. He plays soprano, alto and tenor saxophones and flute, and on some records the electronic wind instrument. The jazz side is real but secondary: Berklee training, the All American College Band chair, a decade inside a GRP and Peak band, session work with jazz players such as Brian Bromberg and the pianist Russell Ferrante, saxophone parts on David Benoit's Earthglow (2010), and a straight-ahead streak that AllMusic says still colors his live sets. AllMusic names Mangione and Spyro Gyra as his early influences, and on Luminoso he moves from radio pop-jazz to Brazilian songbook material. He belongs to the same smooth jazz radio generation as Kenny G and Kirk Whalum, and to the line of Rippingtons saxophonists that runs through Paul Taylor and Eric Marienthal.