Australia batsman George Bailey is to join Middlesex at the end of next month.
Bailey, Middlesex's fourth overseas signing of the summer, will be available from late June until the middle of August.
The 33-year-old, Australia's former limited-overs captain, has 104 caps for his country across the formats.
He will replace his compatriot Adam Voges during the Middlesex captain's mid-summer absence on Test duty in Sri Lanka, and joins New Zealanders Brendon McCullum and Mitchell McClenaghan as the latest overseas recruit at Lord's this year.
Middlesex's managing director of cricket Angus Fraser said: "Obtaining high-quality overseas player cover for an entire season is extremely difficult, and everyone at Middlesex is delighted that we have been able to acquire the services of a player of George's ability.
"George is an outstanding cricketer with an excellent record in all forms of the game - and as someone who has captained his country, he will be a valuable addition to the squad both on and off the field.
"George's county championship availability may be slightly affected by Australia's schedule and selection, but he will be available for all our T20 Blast and one-day cup group-stage matches during an important and busy period of the summer between the end of June and mid-August.
Bailey, who played for Sussex last summer, added: "I can't wait to get over there.
"I'm itching to play in the UK again after a productive and enjoyable stint last year.
"Playing at Lord's is an absolute honour. Who wouldn't want to have Lord's as their home ground?"