| Ferdinand Maximilian I | |
| Count of Ysenburg-Büdingen-Wächtersbach | |
| Reign: | 1673 – 14 Mar 1703 |
| Predecessor: | Johann Ernst I, Count of Isenburg-Büdingen |
| Successor: | Ferdinand Maximilian II, Count of Ysenburg-Büdingen-Wächtersbach |
| Birth Date: | 3 January 1662 |
| Birth Place: | Büdingen |
| Death Place: | Wächtersbach |
| House: | Isenburg |
| Issue: | Ferdinand Maximilian II, Count of Ysenburg-Büdingen-Wächtersbach |
| Father: | Johann Ernst I, Count of Isenburg-Büdingen |
| Mother: | Countesd Maria Charlotte of Erbach-Erbach |
Ferdinand Maximilian I of Isenburg-Wächtersbach was a German count of Isenburg-Wächtersbach from 1673 to 1703, and was the first of that county, (which was located near the center of the Holy Roman Empire), and the father of Ferdinand Maximilian II of Isenburg-Wächtersbach. The county lasted from 1673 to 1806, until it was mediated to Isenburg.