Beckford, on loan from Leicester, stepped off the substitutes' bench to fire two goals in Huddersfield's win at Wolves last Saturday and followed up with another brace in today's lunch-time kick-off.
The Jamaica international, making his 200th league start, struck a goal in each half against Kenny Jackett's beaten FA Cup semi-finalists to sandwich James Vaughan's neat finish early in the second period.
But both players were later forced out of the game through injury and could be doubtful for Huddersfield's final two matches.
Beckford took his tally for the season to eight, while Vaughan struck his 10th to help lift Mark Robins' side three points clear of the drop zone, albeit briefly with all their relegation rivals scheduled to kick off at 3pm.
Huddersfield secured their first home win in four to give their survival hopes a huge boost against a Millwall side that had bounced back from last Saturday's Wembley disappointment with a midweek win over Watford, which effectively secured their safety.
Beckford went close to giving Huddersfield the perfect start in the seventh minute, forcing Millwall goalkeeper David Forde into a fine save with a thumping header from 12 yards.
But Millwall enjoyed an equal share of early possession and went even closer to the opening goal when midfielder James Henry slammed a 25-yard shot against the crossbar from Jack Smith's tapped free-kick.
Huddersfield pair Oscar Gobern and Vaughan both shot tamely off target with clear-cut chances at a premium before Beckford broke the deadlock in the 37th minute.
The former Leeds forward was given too much space in the visitors' penalty area and curled an angled shot from 12 yards inside Forde's left-hand post.
It was no more than the home side deserved and they almost doubled their lead less than 60 seconds later when right-back Jack Hunt's fierce drive from inside the area was brilliantly saved by Forde.
For all Town's domination during the latter stages of the first half, Millwall would have snatched an equaliser before the interval had it not been for Huddersfield goalkeeper Alex Smithies, who turned away another goalbound strike from outside the area by Henry at full stretch.
Smithies was tested again shortly after the restart when keeping out Millwall midfielder Martyn Woolford's close-range effort.
That was Woolford's last contribution before he and Shaun Batt were replaced by strikers Rob Hulse and Jermaine Easter, but visiting manager Jackett's bid to chase the game was made doubly hard in the 55th minute when Vaughan slotted home Adam Clayton's pass from the edge of the area.
Vaughan then turned provider for strike partner Beckford, laying on a superb pass for the Jamaica international to run on to on the edge of the box and lash home, high into the net.
Town substitute Lee Novak's angled drive was well saved by Forde in the closing stages as the home side comfortably held on to their three-goal advantage.
- Sports & Recreation
- James Vaughan
- David Forde