An injury meant Kitson was only fit enough for the bench when Reading were beaten at home by Plymouth on Saturday.
Coppell restored last season's leading scorer to the starting line-up and was rewarded with a convincing win.
Glen Little had already given the visitors a first-half lead when Kitson pounced to wrap up the points in the 63rd minute.
The former Cambridge hitman met Nicky Shorey's cross with a powerful header from close range.
Wayne Henderson, making his home debut in Brighton's goal on loan from Aston Villa, got both hands to it but could not prevent the ball from crossing the line.
Little had given Reading a flying start with his first goal for two seasons after 15 minutes.
The former Burnley winger whipped in a free-kick from 35 yards which eluded everybody in a packed penalty area, leaving Henderson rooted to his line.
Brighton's new keeper kept his team in touch with two fine saves in the first half.
He stretched to hold a shot on the turn from Leroy Lita, Reading's £1million summer buy from Bristol City, after the England under-21 international linked up with Kitson.
Henderson then turned away a fierce drive from outside the box by Steve Sidwell.
Brighton, with four new signings in their starting line-up, offered little by way of response.
Colin Kazim-Richards, their teenage striker signed from Bury, was their biggest threat.
He forced Marcus Hahnemann into a low stop with a turn and volley from a Kerry Mayo cross then produced a cross-field pass for Paul Reid to unleash a fierce effort which Hahnemann dived to push round the post.
Brighton looked capable of getting back into the game in the second half but Kitson's goal killed them off.
Lita should have added a third for Reading in the 78th minute when he headed wide from substitute John Oster's cross.