The firm also reported a revised figure for July that pegs job gains for that month at 109,000, rather than the 114,000 previously reported.
The figure for August came in about 10,000 shy of economists' expectations and shy of the number required to lower the 9.1 percent unemployment rate, as about 130,000 adults enter the workforce each month.
ADP said small businesses added 58,000 jobs, while businesses with 50 to 499 employees added 30,000. Larger firms, those with 500 or more workers, added 3,000 jobs, even less than the 9,000 large firms added to their payrolls in July.
Separately, employment consulting firm Challenger, Gray & Christmas said U.S. firms announced plans to layoff 51,114 workers in August, a drop of 23 percent from July, when 66,414 layoffs were announced.
It is hard to declare a trend in layoffs at this point. July's layoffs were a 16-month high for the category. August only defines a declining trend of one month and the total for August was 47 percent higher than the 34,768 layoffs announced in August 2010.
The hiring pattern has held through the recovery, however. Major corporations remain reluctant to hire with small firms doing the bulk of the new hiring.
ADP said service sector jobs gained by 80,000 in August, while goods-producing firms added 11,000 jobs after losing 17,000 jobs a month in July.
Manufacturing in August lost 4,000 jobs after losing 1,000 in July.
After three consecutive months of declines, the number of construction jobs rose by 7,000.