The takeover proposal, in which Mars is offering Wrigley's investors about £40 a share, is one of the largest in recent years and will result in combined global sales of more than £13.5m.
It brings together some of the world's best-known confectionery brands including Orbit, Extra, M&Ms, Snickers and Mars plus a number of leading food, drink and pet care brands.
As part of the deal, Berkshire Hathaway will purchase a minority stake in Wrigley's worth just over £1bn.
In the US, Wrigley's will become a separate, standalone subsidiary of Mars, with Mars' non-chocolate sugar brands added to Wrigley's portfolio.
No plans have yet been announced for the UK divisions of the two companies.