Australian Test vice-captain Steve Smith has confirmed he will play three games for Sussex in the County Championship before the Ashes get underway.

In a year where Smith already has the home summer, Australia's Border-Gavaskar trophy tour of India, the Ashes in England, a possible World Test Championship final and the ODI World Cup back in India before another home summer gets underway, he has confirmed he will join Sussex for an all-important tune up ahead of the Ashes for three games.

The three games Smith will play for Sussex will all occur during May, with the World Test Championship final - which Australia will almost certainly qualify for - will be played during the first fortnight of June, directly before the Ashes get underway.

Smith said he was excited to join Sussex.

"I am excited about joining Sussex for a few games in May and hopefully making a contribution to a successful season," Smith said in a statement.

"I am particularly looking forward to working with the younger players in the squad and hoping I can provide some guidance to them."

Sussex cricket CEO Rob Andrew labelled Smith as the world's best batter.

"We are thrilled to have Steve Smith available for our County Championship matches in May. To have arguably the world's best batter play for Sussex just before an eagerly awaited Ashes Test series is great for us and the County Championship," he said.

"Our Championship form has not been good enough for a number of years, and under the new direction of head coach Paul Farbrace, we are looking to be positive and ambitious.

"Being able to attract a player of Steve Smith's calibre is a massive statement and will be of great benefit to our young homegrown players, particularly our crop of talented young batters."

But it's a decision which has not gone down well with all of English cricket, with captain Ben Stokes previously suggesting he would prefer to see Smith not given opportunities to tune up in English conditions.

"It's one of those where you probably prefer them not to get any game time in England before the Ashes," he said.

Smith has scored 1727 runs in 16 Tests on English soil, averaging 61.41.