Houllier, who ruled out the possibility of a transfer window departure by Ashley Young, said the Borussia Monchengladbach midfielder was undergoing a medical before completing a loan until the end of the season.
"Bradley will be signing, hopefully," said Houllier. "We've got to prepare for the future and Michael is 23 and a very hard working midfielder who can score goals."
Turning to England forward Young, reported to be a target for Liverpool, Houllier said: "I can confirm that Ashley is a highly-rated player and highly liked by everyone at Aston Villa. No way is he going to leave."
Meanwhile, Stephen Ireland is set to move out of Villa Park on transfer deadline day, with his loan move to Newcastle almost completed.
Houllier said: "I think it's (Ireland's move) on the way."
Out-of-favour left-back Stephen Warnock has been linked with a possible loan move to former club Liverpool or Wigan but Houllier said "so far nothing has happened".
Bradley is the son of USA head coach Bob Bradley and was part of their World Cup squad in South Africa last summer. He has 18 months left of his current deal with Monchengladbach.
Villa have already signed Darren Bent, Jean Makoun and on-loan Kyle Walker during the transfer window.
Source: PA
Source: PA