The second phase of the Google Art Project, which was announced in February, has seen the firm add sculptures, street art and photographs from venues in 40 countries.
The website - which goes live on Wednesday morning - will offer 30,000 works in collaboration with the likes of the Metropolitan Museum of Art (Munich: A0DKUE - news) in New York (Frankfurt: A0DKRK - news) and the National Gallery, in London.
Others, such as the Hermitage in St Petersburg, the Uffizi in Florence and the National Gallery of Modern Art in Delhi, are also included.
Some of the images have been photographed in detail using super high-resolution "gigapixel" cameras, enabling the viewer to study the brushwork and details that can be missed by the naked eye.
Google say they want to bring masterpieces that are often reserved for the privileged few to a wider audience for free.
Amit Sood, head of Google Art Project, said: "You get to travel from your computer to some of the greatest museums in the world, but also some of the museums in the world that you've never heard of.
"You can explore individual pieces of art like you've never done before."
However, some say the technology cannot replace a real visit to a gallery.
Rachel Campbell-Johnston, chief art critic for The Times, said: "We treat art as a sort of cultural parallel to a spiritual experience.
"The idea that you go on a pilgrimage to find an artwork, you discover it, you stand in front of it and it's embodied in the whole experience of the artwork - it's how you got there, how you felt, the effort you made.
"Google Art obviously gets rid of a lot of that. You just push a button and there it is."