Spurs were in complete control from start to finish and a strike in each half from Son secured them a fourth successive home Premier League win.
With the victory, Mauricio Pochettino's side open up a five-point cushion on fifth-place Chelsea who travel to runaway leaders Manchester City on Sunday.
The Huddersfield goalkeeper was exposed for Son's first goal by Florent Hadergjonaj stepping up and attempting to play offside, which allowed the South Korean to latch onto Dele Alli's through-ball and round Lossl before finishing calmly with his left foot.
Lossl continued to keep Kane off the scoresheet though, denying the striker a 36th goal of the season with a strong one-handed save, at the end of a first half in which Hugo Lloris went untested at the other end.
The only save of note enforced upon the Frenchman was from a powerful 25-yard drive from substitute Tom Ince 10 minutes into the second half, and Spurs responded by doubling their lead within 60 seconds.
It may not have been Kane's day in front of goal, but he did produce a contender for assist of the season with his deep cross which picked out the run of Son, who skilfully steered a header back across Lossl and inside the post.
Jan Vertonghen was denied a first league goal in five years by the offside flag, after he had headed Christian Eriksen's set piece beyond a stranded Lossl, but Spurs were otherwise content to sit on their two-goal cushion.
With the Terriers offering little attacking threat, Pochettino had the luxury of resting Son, Alli and Mousa Dembele in the final quarter ahead of Wednesday's Champions League showdown with Juventus at Wembley.
TOTTENHAM (4-2-3-1): Lloris; Aurier, Sanchez, Vertonghen, Davies; Dier, Dembele (Sissoko, 73'); Eriksen, Dele (Lucas, 83'), Son (Lamela, 70'), Kane
HUDDERSFIELD (4-5-1): Lossl; Hadergjonaj, Zanka, Schindler, Kongolo; Hogg (Depoitre, 83'), Williams; Quaner (Ince, 33'), Pritchard (Billing, 45'), Van La Parra, Mounie