South Carolina Governor Nikki Haley was nominated as US envoy to the UN and Betsy DeVos as education secretary.
Both are former critics of Mr Trump, with Mrs Haley once saying she was "not a fan", and Mrs DeVos branding the Manhattan tycoon an "interloper".
Mr Trump's presidential primary rival Ben Carson also hinted he would soon be named for a post.
"An announcement is forthcoming about my role in helping to make America great again," Mr Carson wrote on Facebook.
