[3][4] Barker contributed to three songs on the Zero 7 album Simple Things (2001), including their biggest hit, Destiny, accompanied by fellow vocalist Sia.
Barker has also worked with The Egg ("Walking Away"), electronica artists Grooverider (Time, Space), Groove Armada (Inside My Mind (Blue Skies), Your Song) and the acid-jazz duo Muki ("I Don't Want to Know").
Barker was featured in a 2006 British Airways UK television campaign, singing a cover version of John Denver's Leaving on a Jet Plane.
Barker also featured as a guest singer on Quiet Letters by Bliss, and then collaborated and provided vocals for their album entitled No One Built This Moment.
[7] She also appeared on CeCe X’s all female synth pop EP ‘Synthgirl Squad’, duetting and co-writing on the track, ‘Take Me Away’, released in 2017.