The design (pictured) appears next to the interactive search box when users type in the words 'gay' or 'lesbian'.
Google Operating System said in a blog post: "It's not the first June when Google changes the search results interface when you search for [gay] and other related terms.
"While in 2009 and 2010 Google added a colorful bar below the search box, this year there's a rainbow next to the search box."
Previously, Google have been vocal about supporting the repeal of Proposition 8 and recently produced a video in support of the It Gets Better campaign.