Moncur, 20, made nine appearances for the O's last season in Sky Bet League Two, and following the expiration of his previous contract expire on June 30th has agreed new terms with the club.
A graduate of the O's youth system, Moncur penned his first professional contract in E10 last summer and will add depth to Head Coach Steve Davis' midfield for the upcoming 2017-18 National League season.
Speaking on the decision to offer Moncur a new deal, director of football Martin Ling told the club`s official website: "I felt that Freddy performed well here last year and that it would be good to fetch him back in to the club.
"I know he had trialled elsewhere during the summer, but I believe he goes in well to the bracket of young players that we have here who can be a good squad member.
"I saw Freddy play quite a lot when he was part of the Youth Team here, and although I haven't seen much of him over recent years I believe he deserves this opportunity".