Of course she was. From 1981 to 1983, Tappi Tíkarrass was a well-known Icelandic punk band who distinguished themselves from the usual crowd of punks by adding elements of funk and jazz to their music. The band got their name when the original lead singer's father said the band's music “fitted like a cork in a bitch’s ass." Within months of their formation, Björk took over the lead singer role.
After a couple of years, the band's members disbanded to pursue different things, and Björk moved on to her next project, the gothic, anarcho-punk band KUKL. KUKL translates into ""witchcraft" in Medieval Icelandic.
Here's Tappi Tíkarrass performing in 1982:
Here's another performance from London, also in 1982: