Luke Ronchi is returning to Somerset as an overseas player for the last four matches of the County Championship.
The 34-year-old New Zealand wicketkeeper played in five T20 games for the county earlier this summer.
He will be available to play against leaders against Yorkshire at Headingley, starting on 1 September and the three games that follow.
"I have always wanted to play Championship cricket in England," Ronchi told the club website.
"I look forward to putting in some good performances for Somerset over the rest of this season."
Ronchi made his Test debut against England earlier this year and is currently on tour with the Black Caps in South Africa.