Since being completed in 2019, it connects the Istanbul and Kocaeli metropolitan areas with İzmir, via Bursa and Balıkesir.

The O-5 runs parallel to the D575 and the D565 for most of its length and is a major motorway in Turkey as it provides a direct connection between Kocaeli and its surrounding metropolis to the country's 3rd largest (İzmir) and 4th largest (Bursa) cities, bypassing the Gulf of İzmit via the Osman Gazi Bridge.

The rest of the O-5 has been under construction since the early 2010s, with the first portion opened from Altinova to Gemlik in April 2016.

The O-5 is the most expensive toll motorway in Turkey as the price for a personal vehicle from Kocaeli Gebze to Izmir 147 km (91 mi), ₺ 984 (US$ 29.76), including the Osman Gazi Bridge toll of ₺ 399.00 (US$ 12.07).

It is a build-operate-transfer project which was awarded to a consortium consisting of 5 companies (Nurol, Özaltın, Makyol, Göçay and Astaldi).