At the award ceremony in London last night, editor Katrina Lloyd was awarded the trophy by Kames Capital chief executive Martin Davis.
This is the second time Investment Week has won this award, having previously won in 2015.
The Kames Capital Journalism Awards aim to recognise outstanding investment journalism.
Davis said: “The ability to convey investment content in an interesting, informative, and insightful way is an admirable skill and one which should be celebrated.
“The Kames Capital Journalism Awards do this, recognising the talent of investment journalists, across both trade and national media.”
Last year, Investment Week was awarded the prize for Excellence in Investment Writing at the Investment Association awards.