Murray Goodwin has signed a new three-year contract with Sussex, subject to confirmation that he can be registered as a non-overseas player.
Goodwin has scored more than 5,000 first-class runs for Sussex
Goodwin has spent the past four years at Hove and was a member of the 2003 Championship-winning side.
The club said all indications were that registering Goodwin as a Kolpak player "will not be a problem".
Director of Cricket Peter Moores said they now hoped to fill their overseas vacancy in the next couple of weeks.
"Our decision to sign Murray as a Kolpak player was not taken lightly due to the need to keep places available for our own home-grown players.
"Murray's commitment to the club and his ability as a player are without question and we are delighted that he has decided to commit to us for the foreseeable future," Moores added.
The Kolpak ruling states that "any citizen of a country with an associate agreement with the EU has the same rights as a European worker".
It is named after Slovakian handball player Maros Kolpak, who went to the European Court in a bid to play in Germany without being classed as a foreigner, claiming restraint of trade.
A number of county clubs have taken advantage by signing players from Zimbabwe and South Africa, although Goodwin has until now been classed as an overseas player.
The 32-year-old spends his winters playing state cricket for Western Australia.