Player coach Davids, a Champions League winner, not only took the captain's armband on his Bees debut but it was his first competitive game since running out for Crystal Palace in a 3-0 defeat to Swansea on October 30 2010.
But the 39-year-old clearly had an impact as second-half goals from Krystian Pearce, Andy Yiadom, John Oster and Anthony Edgar saw the hosts comfortably home at Underhill.
Northampton had the best of a poor first half but 10 minutes after half-time Barnet went ahead, Davids earning his side a corner and on-loan Notts County defender Pearce heading his first Barnet goal.
And 10 minutes later Yiadom's deflected shot flew into the top-right corner of Lee Nicholls' net to put the home side firmly in control.
But Barnet weren't done there, Oster driving superbly home from 20 yards with a minute of normal time left and Edgar wrapping up the points in injury time with a strong effort.