Sigler was born on March 17, 1941, in Philadelphia,[1] and was nicknamed "Bunny" by his family as a young child. He sang in churches, and joined several local doo-wop groups, including the Opals, in which he sang with his brother James Sigler, Ritchie Rome and Jack Faith.[3] By the late 1950s, he had started performing in local venues as a singer and pianist, and he first recorded for the V-Tone Records label in 1959. Leon Huff then recommended him to record producersJohn Medora and Dave White at Cameo-Parkway Records. His second single for the Parkway label, a medley of two Shirley and Lee hits, "Let the Good Times Roll & Feel So Good", rose on both the national pop and R&B charts, reaching #20 R&B and #22 pop in 1967. The follow-up, another medley, this time of two doo-wop songs, "Lovey Dovey"/"You're So Fine", also reached the R&B chart in the same year.[2][3]
After Cameo-Parkway folded, around 1970 Sigler began working as a songwriter with Kenny Gamble and Leon Huff at Philadelphia International Records. In partnership with writer Phil Hurtt, Sigler wrote songs for the O'Jays including "Sunshine" and "When the World Is at Peace". He also wrote songs solo and with Gamble, and his compositions were recorded by many of the Philadelphia International artistes. He discovered a group, Instant Funk, and began again recording as a singer. He had his first chart success for six years in 1973 with a remake of the Bobby Lewis hit "Tossin' and Turnin'" (#38 R&B, #97 pop), and had several further minor R&B chart hits on Philadelphia International in the mid-1970s, including his version of "Love Train", and "Keep Smilin'". He also released several albums in the mid-1970s, on which he was backed by the MFSB musicians as well as Instant Funk.[2][3]
Sigler continued to work as a songwriter and producer for artistes including the Whispers, Ecstasy, Passion & Pain, Carl Carlton, Jackie Moore, Harold Melvin & the Blue Notes, The Roots, Billy Paul, Lou Rawls, Patti LaBelle, Stephanie Mills and Curtis Mayfield. He also appeared on "Soul Train" where he sang his song, "That's How Long I'll Be Loving You", and released a duo album with Barbara Mason. In 1977, he moved to the Gold Mind label, set up by MFSB musician Norman Harris and distributed by Salsoul Records. There, he had his biggest R&B hit, reaching #8 in early 1978 with "Let Me Party With You (Party, Party, Party)". He also continued to work with Instant Funk on their breakthrough hit "I Got My Mind Made Up (You Can Get It Girl)", and with other acts on Salsoul. In 1978, his recording with Loleatta Holloway, "Only You", reached #11 on the national R&B chart and #87 on the pop chart.[2][3]