The 20-year-old Wales U21 international will remain at St Andrew's until Saturday, March 1.
Hughes will join fellow City midfielder Albert Rusnak at Birmingham after the 19-year-old Slovakia U21 international moved on a one-month loan deal last week.
Hughes has been a regular member of City's Elite Development Squad and made his first-team debut as a 77th-minute substitute in the 5-0 FA Cup third-round replay win over Blackburn earlier this month.
"Birmingham's manager Lee Clark had watched me in a few games for the EDS and made the enquiry to the club and it went from there," Huws, who was called into the Wales senior squad in November, told his club's official website.
"I'm really happy to be joining Albert there, obviously it helps to have someone there I know. The Championship is a really good league and I'm looking forward to getting in there and hopefully proving myself.
"It's also a chance for me to improve as a player and test myself at a really high standard of football."