The number four Stewart-Haas Racing driver made the most of a late restart to take the lead and prevail at New Hampshire Motor Speedway on Sunday, joining Martin Truex Jr. in the quarter-final Round of 12.
Harvick led just two laps through two races after a 20th-place finish last week at Chicagoland put his title hopes in jeopardy, but the 2014 Sprint Cup champion capitalised on a caution to pass Matt Kenseth with six laps remaining.
Kenseth, seeking a third consecutive win at Loudon, finished second after leading 105 laps.
Kyle Busch, Brad Keselowski and Kurt Busch rounded out the top five.
Truex finished seventh after leading 141 of the race's 300 laps.
With one race remaining before a first string of cuts, Jamie McMurray (minus 5 points), Austin Dillon (-5), Tony Stewart (-11) and Chris Buescher (-30) are in danger of being eliminated next week at Dover.