The revamp features a flattened, reshaped logo and replaces the previous menu bar with a smaller range of links on the page's right-hand side.
The move comes in the same month that Yahoo's logo and Microsoft's Bing search tool have also been updated.
A Google spokeswoman said that similar changes would now be "slowly rolled out" across its products.
A blog post added that the firm intended to "streamline" users' experience of its services to prevent "distractions".
It is the first change to Google's logo since 2010. Not all users will be able to see the redesign yet.
"This is the season for consumer tech updates and whether you sell a product or it's free everyone wants to look fresh ahead of the Christmas shopping season," said Sarah Rotman Epps, an analyst at the tech consultancy Forrester.
"What they are doing is actually pretty subtle and that's because these software companies depend on user loyalty - they don't want to do anything that would alienate their customers."
Another analyst suggested that cutting down the number of links would encourage people to use Google's social network, Google Plus.
To reveal other products - such as Google Drive storage, YouTube videos or the Android app Play Store - visitors to the firm's search page must now click on an icon made up of small squares.
"I do think that there is a move to try to make Google+ more central to everything its users do," said Carolina Milanesi from the tech advisors Gartner.
"It might be the case that it is not obvious to some people that they need to click on the box to reveal the firm's other services."
Google has begun rolling out a redesign of its homepage - the world's most visited web address.