The singer-turned-fashion designer once starred in Spice World with her other Spice Girl bandmates, but said that is not something that she plans to repeat.
She told Allure: 'I'm the only person living in Hollywood who a) does not want to act, and b) cannot act.'
The 33-year-old - who is expecting her fourth child with husband David - said that she gets her buzz from knowing the celebrities are wearing her clothes.
She added: 'There's nothing better than being in Los Angeles with my kids, cooking dinner with my husband and having a romantic night in, and I get an email, and Demi Moore, Madonna, Drew Barrymore, Blake Lively, or whoever it is, is doing the red carpet and wearing my dress.'