Brooke Dixon (Clayton, Del./Smyrna) tallied the lone goal for the Green Terror (0-1), converting a penalty stroke at the 25:58 mark.
The Cardinals (1-0) scored three times in the game’s first 17:53 and finished with a 20-5 advantage in the shot column.
Walko notched an unassisted marker at the 2:55 mark to open the scoring.
Abby Banholzer scored off a Meredith Chandler assist at the 12:02 mark before Walko found Ro Dixon nearly eight minutes later.
Erika Wawzyanick (Wantage, N.J./High Point Regional), who was pelted with 14 of the 20 Catholic shots after halftime, made 13 saves, including 10 in the second half.
Marian Cassilly made three stops for the Cardinals.
The Green Terror opens the home and Centennial Conference slate against Washington (Md.) on Saturday. Game time is 1 p.m.
Score by Period 1 2 - F
McDaniel (0-1) 1 0 - 1
Catholic (1-0) 3 0 - 3
C – Carley Walko, 2:55
C – Abby Banholzer (Meredith Chandler), 12:02
C – Ro Dix (Walko), 17:53
M – Brooke Dixon (Penalty Stroke), 25:58
Shots: M 5, C 20. Penalty Corners: M 3, C 14. Saves: M 13 (Erika Wawzyanick), C 3 (Marian Cassilly).