The 26-year-old full-back has agreed a two-year contract at the Abbey Stadium, bringing an end to a four-year spell with the O’s.
“I am looking forward to getting out there and just playing football for this club. We all hope for a strong season, but I’m sure quietly we will believe that there is a good chance to get promoted,” Omozusi told the U’s website.
“Going into next year, the club has got a very good basis having signed some top quality players, so it’s onwards and upwards.”
Omozusi is Cambridge’s fifth summer signing, joining Barry Corr, Leon Legge, Mark Roberts and Keith Keane at the League Two club.
He added: “I have played against Leon a couple of times last season and he is a very good player, which means already it looks like we have a strong team.
“Mark will definitely bring a lot of experience to the side and you need that if you want to do anything in League Two.
“I think we have a strong foundation at the back and will looking threatening going forward too.”