"I am happy and proud that Shimon Peres has decided to join us, in Kadima," Sharon told a news conference on Sunday with Peres at his side.
"I asked Shimon Peres to pick any job he wants. Shimon can fulfil any post, I believe with great success."
Peres, 82, left the Labour party, which voted him out as its leader last month, and threw his support behind Sharon on Wednesday, saying he was confident that the prime minister would seek peace with the Palestinians.
"Regardless of the job Shimon picks, it is crystal clear he will be a full and central partner in the diplomatic process," Sharon said, referring to peacemaking with the Palestinians.
Sharon said he had yet to discuss with Peres, a Nobel Peace Prize laureate, exactly what his job would be under a Kadima-led government after the election on 28 March.
At the news conference, Peres said he was forging a "grand partnership" with Sharon that would pursue Middle East peace and regional economic opportunities.
"I see an opportunity that we must not miss," Peres said. "I wouldn't have been able to forgive myself if I hadn't, because of political party considerations or inconvenience, lent a hand to the move ... Sharon is leading."
"I asked Shimon Peres to pick any job he wants. Shimon can fulfil any post, I believe with great success"
Ariel Sharon, the
Israeli Prime Minister
As vice premier in Israel's governing coalition, Peres helped Sharon to press ahead with a pullout of troops and settlers from the Gaza Strip last September, despite opposition from the prime minister's right-wing Likud party.
Sharon quit the Likud last month and created Kadima, saying he wanted to be free of far-right constraints in pursuing peace.
At the news conference, Sharon reaffirmed his support for a US-backed peace "road map" that charts reciprocal steps towards the creation of a Palestinian state alongside a secure Israel.
But the Israeli leader has said there can be no progress in peacemaking until the Palestinian Authority disarmed fighters as stipulated by the road map, which also calls for a freeze in Jewish settlement expansion in the occupied West Bank.
"I hope the Palestinian Authority will understand this and not miss the opportunity to enter into a diplomatic process," said Sharon, whose vow to retain large settlements has raised Palestinian concern about the possibility of creating a viable state.
The Labour party voted out
Shimon Peres last month
Mahmoud Abbas, the Palestinian president, who declared a truce along with Sharon last February, has said confrontation with fighters will lead to civil war and that he intends instead to co-opt them into the security services and mainstream politics.
A Palestinian parliamentary election, in which the Hamas group will participate for the first time, is scheduled for 25 January.