AFP reports citing the two companies.
But the judge left undecided the $19.9 million payout planned for AMR chief executive Tom Horton, who will lose his job in the merger.
"Judge Lane's approval of the merger agreement today allows us to continue progressing forward with our planned merger and we are gratified to know that he considers the merger an 'excellent result' for stakeholders," American and US Airways said in a joint statement.
"The court approved the merger agreement but deferred ruling on Mr. Horton's compensation arrangement."
Some American Airlines creditors have reportedly raised objections to Horton's payout, as the company emerges from bankruptcy restructuring and goes ahead with the merger.
The combined airline, to keep the American Airlines name, is to be led by current US Airways chief executive Doug Parker.
US Airways shares were up 2.8 percent to $17.12 in after hours trade following the news.