A topping out ceremony was held on top of its tallest building and visitors were given tours of the development, which will complete early next year.
Edward Street Quarter's highest point is just over 31m, and the six buildings will accommodate offices, retail and hospitality facilities and new homes.
Businesses also had the opportunity to walk around their future office or leisure space as the countdown to completion next year starts.
Steve Eccles, Project Director at First Base, said:
"Reaching the highest point of Edward Street Quarter is a real milestone for the development.
"We were so excited to welcome our guests for tours of Brighton's newest neighbourhood and show them the breath-taking views from the top.
"With Grade A office space, new homes, retailers, cafes and leisure facilities, as well as green spaces and inspiring public art, Edward Street Quarter is set to become a destination in its own right.
"We are on track to complete next year and welcome occupiers, visitors and the local community alike."
Edward Street Quarte
r comprises 125,000 sq ft of flexible space for Brighton's burgeoning digital and creative sectors
and wider corporate community, making it the largest provision of workspace to be delivered in the city since 1993.
20,000 sq ft is also set aside for retailers, leisure and hospitality. 168 new homes are available, comprising a mix of private and affordable units to meet local demand.
The development includes design features to boost mental and physical wellbeing as well as three public green spaces, heavily planted with mature trees and an edible garden full of herbs.