Slack play at the back contributed to this defeat at Charlton the Magpies' fourth in a row which ended Newcastle's nine-match unbeaten sequence against the London club.
Scott Parker's brilliant 35th-minute equaliser was one of the few bright spots for the Magpies, who were sunk by Darren Bent's 23rd-minute penalty, a freak own-goal from Lee Bowyer and a late header from substitute Jay Bothroyd.
Against the run of play, Charlton won a penalty in the 23rd minute after Craig Moore was adjudged to have brought down Jerome Thomas, and Darren Bent struck his 20th goal of the season into the bottom-left corner from the spot.
The goal lifted Charlton's confidence visibly, but former Charlton player Parker who had been booed throughout the first half then silenced his detractors with an exhilarating strike in the 35th minute. Collecting Shearer's square pass from the left, Parker hit a perfect shot into the Charlton top-right corner from 30 yards.
But the delight was short-lived, as Charlton regained the lead in bizarre fashion 60 seconds later.
After Hermann Hreidarsson had won Chris Perry's free-kick in the air, Moore whacked his clearance against the back-tracking Bowyer, who could only watch in horror as the ball cannoned into his own net from six yards.
Alan Curbishley's team made the points safe when substitute Jay Bothroyd with his first touch headed in a near-post cross from fellow sub Dennis Rommedahl two minutes from full-time.
CHARLTON: Myhre, Young, Perry, Hreidarsson, Powell, Kishishev, Holland, Hughes, Thomas (Rommedahl 76), Marcus Bent (Bothroyd 88), Darren Bent.
NEWCASTLE: Given, Carr, Boumsong, Moore, Ramage, Solano (Dyer 45), Bowyer, Parker, Emre, Shearer, Ameobi (N'Zogbia 71).
Referee: M Halsey (Lancashire).