Charlton were relegated from the Premier League after Dimitar Berbatov's superb strike set up Tottenham's 2-0 win at the Valley on Monday.
Alan Pardew's side needed a victory to retain any hope of avoiding the drop, but they never recovered from Berbatov's early goal and Jermain Defoe's last-minute effort confirmed their return to the Championship after seven years in English football's top division.
The result also ensured Fulham retain their Premiership status and leaves Wigan, West Ham and Sheffield United fighting to avoid the final relegation place.
Charlton paid the price for a dismal first half of the campaign under the management of Iain Dowie and then Les Reed. Pardew, their third boss of the campaign, inspired an impressive revival after taking over at Christmas with the club looking dead and buried.
But the south London team slipped back into trouble in the last month and a run of six matches without a win left them facing the unappetizing prospect of trips to Scunthorpe and Colchester next season instead of Chelsea and Manchester United.
Spurs move into sixth place and remain on course for a UEFA Cup spot after winning the first of three games in six days that will determine whether a season that promised so much ends with a tangible reward.
A win over Blackburn tomorrow will clinch another European adventure for Martin Jol's side.
Charlton knew only two victories from their last two games would be enough to beat the drop. But with just 90 minutes to save their season, they inevitably looked nervous.
Anxiety
That anxiety showed in the fifth minute when Darren Bent played a quick corner to Darren Ambrose and his cross picked out Marcus Bent, but the Charlton striker swung wildly and completely missed his kick.
Spurs made them pay in the seventh minute with a goal that underlined why Chelsea and Manchester United are so keen to sign Berbatov.
The Bulgarian's sublime flick wrong-footed Talal El Karkouri and he showed great strength to hold off the defender as he sprinted into the area before steering his shot into the far corner.
Charlton enjoyed a spell of sustained pressure after that chance, but a half-hearted appeal for a penalty when Michael Dawson tacked China midfielder Zheng Zhi was the closest they came to threatening Robinson's goal.
Pardew's last throw of the dice was to send on Jimmy Floyd Hasselbaink for the final 20 minutes.
The veteran striker forced a brave save from Robinson. But when former Addicks forward Defoe ran on to Berbatov's pass and beat Carson with a clinical finish in stoppage time, Charlton's fate was sealed.
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