The Nigeria international teamed up with the Cucumber Growers at the start of last summer for his sixth loan spell away from Stamford Bridge, having featured for ADO Den Haag, Middlesbrough, Kasımpasa and Alanyaspor.
Omeruo impressed during his temporary stay, helping Mauricio Pellegrino’s men to keep 11 clean sheets in 31 appearances across all competitions.
Satisfied with the showings from the Super Eagles defender, the Cucumber Growers paid a fee around £4.6 million to the Blues to secure his permanent signing.
The 25-year-old Omeruo, elated with the deal, has taken to the social media to express his feelings.
“I am so happy to be joining a team that helped me grow so much last season,” he posted on Instagram.
“I can’t wait to start and help this team achieve greatness,” he concluded.
Omeruo will hope to kick on from where he stopped last season when Leganes take on Osasuna in their opening league game of the season on Saturday.