Jorginho converted an early penalty before Reece James and Kurt Zouma sealed the three points with second-half strikes after Leandro Trossard leveled the score for Brighton in the 54th minute.
Frank Lampard’s men got off to an ideal start after 23 minutes. New signing Timo Werner drew a penalty after he was taken down by Brighton goalkeeper Mat Ryan, and Jorginho stepped up to give the Blues the lead.
Chelsea kept their advantage into half-time but Trossard equalised nine minutes after the break to settle the hosts.
However, James struck back moments later with a rocket from well outside the box and Zouma added a third 10 minutes later with a side-footed volley from a James corner that took a wicked deflection before beating a helpless Ryan in goal.
Chelsea next face champions Liverpool in a juicy Premier League encounter on Sunday. While Brighton will host Portsmouth in an EFL Cup second round match on Thursday before visiting Newcastle in the league on Sunday.