The changes, which will continue a shift in policy since 2011, will be made before 2016.
"New frontier markets will be added to our equity investments and the scope of our fixed-income investments will be widened to include additional currencies," the fund said in a statement on Tuesday.
The fund, worth about $173,000 for every man, woman and child in Norway, invests in more than 8,000 firms and across 82 countries. It owns 1.3 percent of the world's listed companies, including 2.5 percent of European ones.
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Set up as a sovereign wealth fund in 1998, the fund's net annual return has lagged its 4 percent target, prompting a shift in its investments three years ago from Europe to emerging markets. It invests in stocks, bonds and real estate only.
The fund has said it plans to take a more active role in some of the firms it invests in, increasing its stake in those companies to over 5 percent. On Tuesday, it said it aimed to increase their number to 100 by 2016, and that two-thirds of them would be in Europe.
As of Dec. 31, the fund held stakes of more than 5 percent in at least 10 companies, including Finnish forestry firm Stora Enso <STERV.HE> and Hong Kong's China Water Affairs Group Ltd <0855.HK>.