Opera Mini will become the default browser for all of Microsoft's Nokia-branded Series 30+, Series 40 and Asha devices.
Customers who already have a low-end Nokia device running the Xpress browser will be encouraged to download and install the Opera, while all new devices shipped will have the software pre-installed.
Opera Mini works across all devices - whether running Android, iOS, Windows Phone or older versions of Symbian. It compresses web pages so they are more suited to small screens and allows customers to save on mobile data charges.
Lars Boilesen, CEO of Opera Software, said: "This is a great opportunity to spread the benefits of Opera Mini to millions more consumers in our core markets. There are still massive numbers of people who have not moved to smartphones, but Opera Mini can provide them with an amazing browsing experience right now."
Microsoft took over Nokia's budget phone business when it bought the company earlier in the year. Although it's not the software giant's core market, addressing the needs of those with lower disposable incomes and the developing markets have always been a key part of Nokia's business.
Rich Bernardo, head of legacy business in the phones division at Microsoft, said: "We continue to sell and support classic first and feature phones as well as the Asha range, which have performed well with millions of people who want new mobile experiences at lower price points.
"The agreement with Opera will enable us to provide continuity of service as we transition from Xpress Browser to Opera Mini."
Around 250 million people use Opera Mini and more than 100 million of these use it on the Android platform.
