The 26-year-old winger brought his season's tally to 12, adding two second-half tries to his seventh-minute opener.
Lam's first try gave the Hurricanes an up-tempo start to the game in blustery, swirling conditions at Westpac Stadium on Saturday.
Both teams were guilty of coughing up possession too easily, but it was the Hurricanes who made the most of their chances.
The late loss of Jordie Barrett to an ankle injury didn't affect their running game, with Nehe Milner-Skudder slotting in at fullback in his second game after returning from shoulder surgery.
Ardie Savea finished Matt Proctor's initial break after the Lions' lineout - missing hooker Malcom Marx to injury - misfired on halfway in the 25th minute to gift the Hurricanes turnover ball.
The Lions hit back right on half-time, halfback Nic Groom burrowing over from close range to reduce the Hurricanes' lead to 14-7 at the break.
But two Lam tries within the space of 10 minutes extended the Hurricanes' lead to 28-7, with only flanker Marnus Schoeman's 57th minute try keeping the Lions in touch.
Replacement winger Sylvian Mahuza stole a turnover try with four minutes remaining but the Lions - plagued by handling errors for much of the game - never really threatened.