The £10m investment – which began in April - includes work to improve facilities in the conference centre on the third floor by adding retractable walls to the East Hall.
The aim is to offer greater flexibility to meeting planners by providing more versatile space for smaller breakout sessions.
The new walls mean the space can be divided into three separate rooms, for 250, 170 and 80 delegates theatre-style.
In addition, work has included a revamp of Olympia Two's Level One and infilling the atrium on Level Two.
The existing escalators and stairs between these floors are being removed to produce more effective exhibition space and the ground floor is being reconfigured to create a large traffic marshalling area.
The work is part of a larger investment by the venue's parent company Capital & Counties (Capco), which saw Olympia's West Hall reopen in December as a 9,000sqm, two-storey exhibition facility following a £20m project.
Meanwhile, Olympia Conference Centre’s event management team has secured a 95% rating from event organisers in independent post event research, covering responsiveness in planning stages, ability to get things done, availability on site and rapport.
Gillian Kiamil, Olympia’s interim deputy halls director, said: "It’s an exciting time for both Olympia and our conference business so we’re looking forward to building on such positive foundations once the venue re-opens in September."
Feedback from clients included The Business Continuity Institute, organiser of BCM World Conference & Exhibition.
Its head of events, Lucy Burns said: "Olympia Conference Centre is a great fit for our event. We are excited about the redevelopment which will provide the capacity for more streams and use of an extra floor should the event grow in years to come."