Seventh is their reward for a season which, until the January sale of Scott Parker, promised even more. Charlton have still exposed the efforts of several of the league's over-spending under-achievers.
Southampton, eighth last year and beaten 2-1, end the campaign four places lower, a reflection of their inconsistency and no win in their final five games.
An injury list which, after Anders Svensson limped off within 15 minutes, included 11 players hardly helped. Charlton's second-string appeared at the interval, but most of Saints' reserves played the full 90 minutes.
Alan Blayney, the Belfast-born goalkeeper in just his second game, provided most cause for encouragement for a youthful Southampton side and prevented Charlton's margin of victory from being greater.
Southampton were grateful for Blayney's agility as, after half-an-hour of a soporific end-of-season stroll, the game sprung to life.
His first appearance earned him a 'Save of the Season' accolade; the second featured a flying save from Paul Konchesky's free kick and a point-blank block from Shaun Bartlett.
But he was left exposed and Charlton's supremacy reflected by the lead when Paolo di Canio's first-time pass bisected the visiting defence and Euell sidefooted home. It could prove di Canio's last meaningful contribution in a Charlton shirt; the Italian, out of contract in the summer, was stretchered off before the interval.
By then, his side could have been two ahead, Bartlett volleying past the post and Matt Holland chipping on to the roof of Blayney's net.
The bustling Cole replaced di Canio to bully the Southampton defence and score his side's second goal. Blayney had already denied him once when the on-loan Chelsea striker beat Fitz Hall to Holland's diagonal ball and finished with finesse from an acute angle.
Southampton rallied. Strike partners James Beattie and Brett Ormerod both tested Dean Kiely and the energetic David Prutton scored his first goal for the club from a well-worked move. Ormerod dummied Stephen Crainey's pass and Prutton timed his run for a well-deserved strike.
Perhaps the midfielder caught the goalscoring bug in the summer sun. Having waited 41 games for one goal, he almost had a second within 30 minutes as he met a Beattie flick-on with a fierce half-volley Kiely parried.
It saved Charlton from a draw and earned them over £500,000. Blayney, meanwhile, ended his afternoon by denying Radostin Kishishev a 40-yard wonder goal. It averted embarrassment for the impressive Ulsterman, but mattered less than Kiely's late block.
