The versatile USA international became the club's seventh signing when he penned a two-year deal on Tuesday, bringing the curtain down on a five-year stay at West Ham.
Spector's arrival comes after that of Chris Burke, Marlon King, Morgaro Gomis, Adam Rooney, Steven Caldwell and Boaz Myhill, yet Blues still boast a squad of only 21 with further faces expected to leave before August 31.
And Hughton told Blues' official website: "There is still some work to do on the transfer front because there's a long season ahead and a lot of games to play. We need to have a squad in place that will be competitive in the npower Championship.
"Jonathan is another addition who helps us get closer to achieving exactly that."
He added: "Jonathan is a player who has got experience of playing in the Premier League and as an international for America so he has good credentials. And at 25 he's at a very good age. He is versatile and can play in a few positions. I think he will be a big asset for this club."