A brace from Scott McDonald sandwiched an Emmanuel Ledesma strike as Boro easily beat the Terriers at the Riverside Stadium.
Leaders Cardiff were held to a 1-1 draw at Derby County after Theo Robinson cancelled out Heidar Helguson’s opener.
Crystal Palace, meanwhile, were held to a goalless draw at Hull City, who drop to sixth after Millwall won 1-0 at Wolves thanks to Andy Keogh’s late goal.
Leicester slipped a place to fourth after a 1-0 defeat at a resurgent Leeds United, who clung on to Luciano Becchio’s early penalty.
Brighton are seventh following their 2-0 home win over struggling Bristol City, Dean Hammond and Andrea Orlandi on target for the Seagulls, while Watford go eighth after coming from behind to hammer Sheffield Wednesday 4-1 at Hillsborough.
Ipswich Town surprised Nottingham Forest with a 3-1 win that lifts them out of the relegation zone, while Charlton cemented a mid-table place by beating struggling Peterborough 2-0 in London.
Burnley and Barnsley shared the spoils of a 1-1 draw at Oakwell that leaves the Clarets 10 points and six places clear of the Tykes in 14th, while Blackpool and Birmingham draw by the same score after Tom Ince’s opener was cancelled out by Curtis Davies.