The policy will begin at its US campuses within weeks and then be rolled out globally for its 144,000 employees.
Many firms are weighing up their stances on vaccinations.
Publisher Bloomsbury said in June that vaccines would be compulsory for UK staff returning to offices when they reopen.
Google chief executive Sundar Pichai said in a blog post that "anyone coming to work on our campuses will need to be vaccinated".
How the policy is implemented "will vary according to local conditions and regulations, and will not apply until vaccines are widely available in your area", he said.
In addition, Google will extend the full reopening of its global campuses from 1 September to 18 October due to a spike in cases caused by the Delta variant of coronavirus.
People in special circumstances can apply to work from home until the end of 2021.
However, any Google employee can apply to work from home permanently if they choose, and transfer offices.
Google expects that over time in any given week, 60% of employees will work in the office for a few days each week, one-fifth will be working in new office locations and another fifth will be working from home.
Many firms are weighing up the pros and cons of letting their workforce continue to work from home.
Others have also specified that workers coming into the office need to be vaccinated.
In June, Harry Potter publisher Bloomsbury said staff must have vaccinations ahead of their return to the workplace.
"The simple fact is that this virus is still extremely dangerous," it said.
In the US, JP Morgan said in June that it would instruct staff to log their vaccination status on an internal web portal, with fully-jabbed employees being allowed to discard face masks at work.
Goldman Sachs bankers also have to disclose how many jabs they have had before returning to the office.