Coach Tony Popovic made the announcement at a press conference on Friday afternoon at Parramatta Stadium.
Beauchamp, 31, is a local junior and that played a role in the club's decision.
"It is an honour for myself to lead the team. The coach could have chosen a number of players so I'm really looking forward to leading the team out in the first game against the Mariners," Beauchamp said.
"I am a local boy and it goes to show that no matter what background you come from, the sacrifices you make as a youngster do pay off."
"I'm proud to have grown up in this community and to now represent it is something that I take great pride in."
Beauchamp, who has experienced football in Germany, Denmark and UEA, has played for Melbourne Heart and Sydney FC in the A-League and has been capped more than 20 times for the Socceroos - which included the 2006 FIFA World Cup.
"Michael is a leader, he is an experienced player who has played in many parts of the world and will lead our young squad with plenty of passion," Popovic said.
"Playing at the back of the field, Michael will control things from there and is a great organiser on the field."
Meanwhile, WSW Executive Chairman denied a German report that Michael Ballack had already agreed a deal to become the A-League's latest high-profile capture declaring that "no deal had been done in that regard".
Gorman admitted the team had at least one spot to fill before the start of the campaign and that it was still exploring some options internationally, with Ballack one of them.
"We're flattered by the attention we've received from agents and overseas players in relation to interest in joining our club," Gorman said.
"There's no denying that Ballack is one of those that has been put on the table.
"What we need to do is look at the context of our brand, the club, the culture we're building, the needs of the playing squad.
"We are interested in exploring all the opportunities.
"We look at the possibility of guest players, we look at the possibility of further domestic players. We haven't dismissed anything at the moment."
Western Sydney has two more pre-season matches against Wellington Phoenix (in Christchurch) and Bankstown City Lions before its A-League debut against Central Coast Mariners at Parramatta Stadium on Saturday 6 October.
Carlos Tevez is set to return to Juventus's starting line-up for Friday morning's (AEST) UEFA Europa League semi-final first leg at Benfica.