Hastings replaces former sponsor Britannic Asset Management, and the deal, beginning this year, sees the name of the women's tennis event changed to the Hastings Direct International Championships.
The deal further extends the insurance brand's association with the sport, as it already sponsors the national winter indoor tournament, the Hastings Direct Tour.
The competition is the second most prestigious event in women's tennis in the UK after Wimbledon.
David Gundlach, chairman and CEO Hastings Direct, said: "It is very fitting that we extend our tennis sponsorship with the addition of an international event that not only attracts world-class players and thousands of spectators but is also situated locally to us."
The deal was negotiated on behalf of Hastings Direct by London-based media agency Capitalize with the Lawn Tennis Association.
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