World Rugby released a bid evaluation report by its experts and external consultants, and said South Africa was the unanimous pick.
South Africa, which also hosted the 1995 Rugby World Cup, promised a "triple win tournament" that would deliver "record receipts", a "bucket-list destination" and "the most athlete-centric event in the tournament's history".
Ireland had been the bookmakers' favourites having never been the main host before while France were the outsiders having staged the tournament in 2007. "A new match is beginning, and will play out until the sovereign vote on 15 November".
Ireland finished last in tournament organisation and schedule, venues and host cities and tournament infrastructure.
The board made its recommendation following detailed consideration of the host candidate evaluation report.
Those eligible to vote are: Australia (3 votes), England (3), New Zealand (3), Scotland (3), Wales (3), Italy (3), Argentina (3), Canada (1), Japan (2), Georgia (1), Romania (1), U.S. (1), Asia Rugby (2), Oceania Rugby (2), Rugby Africa (2), Rugby Americas North (2), Rugby Europe (2), South America Rugby (2).
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Instead, the World Rugby Council will meet in London next month to vote on which country will receive the right to host the competition and chairman of Ireland's bid oversight board Dick Spring believes the vote will still go their way.
The last time the World Cup visited South Africa was in 1995; one of the most memorable editions of the tournament as the Springboks defeated the All Blacks in an epic final, it was an event that united a crumbled country.
"This is the first Rugby World Cup host selection to take place following a complete redesign of the bidding process to promote greater transparency and maximize World Rugby's hosting objectives", World Rugby and Rugby World Cup Limited Chairman Bill Beaumont said in a statement.
"It is clear that the evaluation commission is impressed by the quality and detail of the bid put forward on behalf of Ireland". Any bid that crosses the 20-vote mark will be awarded the 2023 World Cup.
The World Rugby Council will make its final decision regarding the 2023 tournament on 15 November 2017.
Ireland has vowed to "compete to the final whistle", adding "nothing in the report is insurmountable".