Businesses added 190,000 jobs last month, up from a downwardly revised 177,000 in July that was previously reported at 185,000.
"The job growth numbers for August improved slightly from July," said Carlos Rodriguez, president and chief executive officer of ADP.
"The employment gains for the month are in line with the year to date average."
The ADP report came two days ahead of the Labor Department's August jobs data.
The department is expected to report Friday that the US economy added 217,000 jobs last month and that the unemployment rate dropped to 5.2 percent from 5.3 percent in July.
"Recent global financial market turmoil has not slowed the US job market, at least not yet," said Mark Zandi, chief economist of Moody's Analytics which helps compile the ADP data.
"Job growth remains strong and broad-based, except in the energy industry, which continues to shed jobs. Large companies also remain more cautious in their hiring than smaller ones."