ADP also said February's gain was higher than previously published. The firm said 230,000 jobs were added to the economy in February, not 216,000.
In March, small businesses, those with fewer than 50 employees, added 100,000 jobs, while medium-sized businesses, those with 50-499 workers, added 87,000 jobs.
Firms with more than 500 workers added 22,000 jobs in February.
After months of negligible gains, March was the second consecutive month in which large firms added at least 20,000 jobs to the economy. March was also the fourth consecutive month in which at least 200,000 jobs were gained in the private sector.
The U.S. Labor Department on Friday issues its employment situation report, which also includes public sector jobs.