The former glamour model - who was previously married to cage fighter Alex Reid and singer Peter Andre - made an appearance at Madame Jojo club`s `Trannyshack` night in Soho, London, and told the crowd she is attracted to both men and women.
After singing Whitney Houston`s `I Have Nothing`, Katie - who has children Harvey, 10, Junior, seven, and five-year-old Princess - announced: "Do you know what, everyone in here tonight is like me. We`re bisexual, I f**k girls. Whatever. I am straight, but I play with the old banjo."
The 34-year-old star also branded Alex - who she separated from in January 2011 after 10 months of marriage - a "tranny" and made lurid revelations about their sex life.
She ended her small stage show with a rendition of Whitney`s `Get Here If You Can` before a drag queen assisted her off stage.
Katie`s sudden outburst about Alex, 37, comes shortly after his former fiancee Chantelle Houghton - with who he has six-month-old daughter Dolly - claimed she discovered sexual texts on the cage fighter`s phone to both men and women arranging to meet during their relationship.
Chantelle, 29, tweeted last month: "I didn`t know Alex cross dressed cos he told me it was a publicity stunt, I found out when I was pregnant.
"not forgetting the hookers he was texting that he`d had orgies with. Forgive me if I look like s**t right now but I f*****g feel it.
"And I`ve texted the guy who he was arranging to meet and told him what I think of him too. F*****g sick dragging me into this. It`s wrong (sic)"