Araujo spent the last two campaigns out on loan in Sky Bet League Two, joining Chesterfield for 2024-25 before moving to Colchester United last season.
Brewers head coach Gary Bowyer welcomed the signing, saying: "We are pleased to be able to bring Harvey to the club. He has experience of playing men's football in Sky Bet League Two, so we look forward to working with him and continuing his development."
Sporting director Richard Dorman added: "Harvey is a really promising young player and someone who perfectly fits the type of player we are looking to work with here at Burton Albion. He is comfortable on the ball, and, more importantly, he is a defender first. To get Harvey here on a long-term deal is fantastic, and we look forward to seeing how he develops in the years to come."
The left-sided defender joined Fulham's academy at the age of 12 and progressed through the club's age groups, featuring in the side that reached the Under-18 Premier League Cup final at 16 before helping the Under-21s beat Tottenham Hotspur to lift the Premier League Cup three years later. He has also represented England at youth level.
Araujo made the step into senior football with his loan move to Chesterfield, making 23 appearances across all competitions in 2024-25 before injury ruled him out of the club's end-of-season play-off campaign. He stayed in League Two for the following season, joining Colchester United and featuring 31 times across all competitions as Danny Cowley's side finished in mid-table.
Araujo had been with Fulham for more than a decade, having originally joined the club's academy, and had signed a new professional contract with the west London club in 2024 to extend his stay there. His departure brings an end to that association as he now looks to establish himself at senior level on a permanent basis with Burton.
Burton begin the new League One season looking to build on last term's campaign, with Bowyer continuing to reshape his defensive options as the transfer window enters its final stretch.