Despite scoring the winner against Watford during the week, Fernando Llorente had to make do with a spot on the bench as Son was preferred to lead the line in Harry Kane's absence.
Spurs dominated the opening exchanges as expected, but they were unable to get the breakthrough inside 15 minutes when Lucas Moura headed wide from six-yards out.
Erik Lamela went even closer just before the 30-minute mark as his header struck the frame of the goal with Martin Dubravka well beaten, although the Newcastle shot-stopper did well to deny Moussa Sissoko minutes later.
The Magpies had to wait until the 51st minute for their first real opening when Deandre Yedlin picked out Salomón Rondon, who steered his header onto the upright.
With an hour played, Mauricio Pochettino eventually introduced Llorente in place of Lucas as the hosts went in search of an opening goal.
Spurs threw everything forward in search of a goal, while Newcastle were quite happy to sit back and soak up the pressure with the hope of catching the hosts on a break.
The deadlock was eventually broken with eight minutes remaining as Son evaded two defenders before firing home from range although Dubravka should have done better.
The North London outfit were able to see out the closing stages to claim victory and move up to second spot in the standings.