Substitute Kazenga LuaLua secured a point for Brighton as Charlton twice threw away the lead.
The Addicks were leading through goals from Lawrie Wilson and Bradley Pritchard, either side of Craig Mackail-Smith's strike.
But eight minutes after climbing off the bench former Newcastle winger LuaLua marked his first appearance since October with the equaliser.
Both sets of fans joined in a minute's applause at 3.07pm to commemorate the moment Colin Walsh hit the net 20 years ago this week, Charlton's first goal since they returned to their Valley ground after a seven-year absence.
And two minutes later the home fans were cheering again when Dale Stephens whipped in a cross which flew in at the far post with Wilson claiming the final touch.
It could have got worse for Brighton but Tomasz Kuszczak palmed Rob Hulse's header over and from the resulting corner, Michael Morrison headed too high.
But the visitors responded well and should have equalised when Mackail-Smith found Gordon Greer in front of goal, only for the defender to scoop his effort over from all of four yards out.
Moments later Charlton goalkeeper Ben Hamer pulled off a fine save to keep out Stephen Dobbie's volley.
But the leveller came in the 28th minute when Morrison made a mess of his clearing header and Mackail-Smith nipped in to tuck away his 10th goal of the season.
Brighton were still in the ascendancy after the break and Hamer parried a fierce drive from Will Buckley before Dobbie fired wide.
Dobbie was left kicking the post in frustration just before the hour mark after wasting another good chance.
Dean Hammond slipped in Buckley to cut the ball back for the former Swansea striker, who slid in to meet the ball but lifted it over the top.
Will Hoskins then teed up Buckley for another crack at goal but his shot was also too high, before Mackail-Smith had an effort deflected wide.
Charlton had hardly troubled Kuszczak since their goal, but with their first genuine chance of the second half they went ahead again.
Johnnie Jackson's low cross ricocheted through the Brighton defence and Pritchard was on hand to sweep the ball into the net for his first league goal.
But three minutes later LuaLua grabbed a point for the Seagulls when his deflected shot wrong-footed Hamer and crashed into the net.