Town followed Tuesday night's 7-0 win over Knaresborough with another victory, though were made to work hard for it by their National League North opponents.
Former Quaker Mark Beck put Town ahead after 22 minutes with the only goal of the first half, before Warren Burrell's cool finish put his side two up five minutes after the restart.
Jarrett Rivers pulled a goal back six minutes after the hour mark, but Town were able to limit the opposition's chances thereafter and secure a second win in four days.
James Belshaw returned to the Town starting line-up after missing Tuesday's pre-season opener against Knaresborough, while six new signings made the starting XI.
Town's number one was called into action inside the opening five minutes, catching an ambitious volley from Stephen Thompson, before Adam Campbell had sent Luke Trotman's low cross wide.
After Joe Leesley's low cross had reached the striker, Mark Beck turned and fired across the face of goal in what was his side's first sight of goal.
Town's number nine got his name on the score sheet in the 22nd minute, heading home Warren Burrell's cross from close range after the right back had edged past his marker on the touch line.
George Smith almost created Beck's second four minutes later with a deep cross from the left, but Chris Elliott somehow scraped the striker's finish off the line at the far post.
Town were in the ascendency and almost doubled their lead as the lively Brendan Kiernan slid the ball through his opponent's legs before firing just over on his left foot.
Despite the lead, the half ended on a sour note for Town as Will Hatfield crashed into George Smith with a late sliding challenge, forcing the left-back to be withdrawn.
Simon Weaver introduced Callum Howe, George Thomson and Lloyd Kerry at the interval, with the latter wasting no time in setting up Kiernan, whose shot was cleared off the line, before forcing a good save from Elliott.
The midfielder then created Town's second of the evening, lofting the ball in behind the Darlington defence to Burrell, who calmly controlled and slotted past the advancing goalkeeper.
The visitors pulled one back after 66 minutes after an attack down the left allowed Jarrett Rivers space 20 yards out, from where the Darlington man was able to beat Belshaw.
The service to Beck kept coming, though the striker couldn't cap an impressive performance with a second goal, though Town saw out the 90 minutes to claim victory.
Harrogate Town: Belshaw, G Smith (Fallowfield 44), Falkingham, Burrell, Beck, Leesley, Kiernan, Stead (Thomson 45), Hall (Howe 45), Brown (Kerry 45), W Smith
Goals: Beck 22, Burrell 50
Darlington: Elliott, Trotman, Liddle (Galbraith 71), Atkinson, Laing (Glover 87), Watson, Rivers, Hatfield (Donowa 76), Campbell (Tyrell 87), Thompson (Bascome 76), Holmes
Subs not used: Hall, Halliday, Bell
Goals: Rivers 66
Referee: Jon Moss