Hogan delivered a much-needed three points with his fourth of the season for City boss Aitor Karanka on the Spaniard's return to Teesside in the Sky Bet Championship.
Karanka spent four years in charge of Boro and he will have enjoyed this one as Birmingham ended a run of six games without a win.
Hogan's 26th-minute winner inflicted a second home defeat of the season on Middlesbrough, who were knocked out of the FA Cup last weekend by Brentford.
Birmingham made things a lot harder for play-off chasing Boro than many would have imagined and recorded a result that was well deserved.
The visitors, who have seen four of their five wins this season recorded away from home, were quick to show they meant business by pressing with intensity.
Had they shown greater creativity in the final third then Middlesbrough, who started poorly, might have been further behind in the first half than they were.
Jeremie Bela was the only Blues player to test goalkeeper Marcus Bettinelli with a routine free-kick curled into him early on.
The game's only goal was Birmingham's best move of the match, when Ivan Sanchez rolled Maxime Colin down the right side of the penalty area.
The full-back's low cross into the six-yard box was perfect for Hogan to tap into Bettinelli's net.
While Birmingham played well and Middlesbrough struggled to get going, the home side created the better chances in the opening period, albeit closer to half-time.
Lewis Wing had already had a header cleared off the line by Mikel San Jose before Sam Morsy's header hit the post, bounced on the line and was then gathered by Neil Etheridge.
On the stroke of the break Marcus Tavernier had a free-kick tipped over by Etheridge before impressive former Middlesbrough skipper George Friend blocked a Chuba Akpom header from going in.
Middlesbrough introduced Britt Assombalonga, Jonny Howson and Djed Spence for the second half and almost immediately should have levelled.
George Saville's little run on the edge of the area led to a chance opening up for Assombalonga but the striker's left-foot finish from 12 yards went wide.
Karanka changed things to protect the lead by introducing an extra defender, and Middlesbrough found it harder to create chances after that.
Etheridge was on hand to deny an effort from Duncan Watmore with a quarter of an hour remaining, while Birmingham did what was required in both directions to stay ahead.
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