Gallaccio was born in Paisley in Scotland and studied at Kingston Polytechnic and Goldsmiths College. In 1988, the year she graduated from Goldsmiths, she exhibited in the Damien Hirst-curated Freeze exhibition which brought together many of the so-called Young British Artists.
Much of her work uses organic materials, with fruit, vegetables and flowers all featuring in her work. Sometimes these materials undergo a change during the course the their being exhibited - in Red on Green (1992), for example, ten thousand rose-heads placed on a bed of their stalks gradually whithered as the exhibition went on. For Intensities and Surfaces (1996) Gallaccio left a thirty-two ton block of ice with a salt core in the disused pump station at Wapping and allowed it to melt.
Other works by Gallaccio include Stroke (1993) in which benches in the gallery and cardboard panels attached to the walls were covered in chocolate and Because Nothing has Changed (2000), a bronze sculpture of a tree adorned with porcelain apples. Because I Could Not Stop (2002) is a similar bronze tree but with real apples which are left to rot.
In 2003, Gallaccio was shortlisted for the Turner Prize.