In his later years, he engaged in pastoral work at St. Francis Xavier Church in New York City and taught at Fordham University.

[3] During his freshman year, he made the first-string baseball team as a shortstop, and remained in this position for the duration of his time at Georgetown.

[3] Here, he was known among his friends by the nickname Al.[5] Donlon received his bachelor's degree in 1888 and subsequently enrolled at the Massachusetts Institute of Technology (MIT), where he studied electrical engineering.

Following his studies, he returned to Georgetown College in 1895, where he assumed a teaching position in physics, mechanics, geology, and astronomy.

On June 28, 1903,[9] he was ordained a priest by Cardinal James Gibbons at Woodstock College,[10] and he completed his theological studies in 1904.

[1][11] On October 10, 1911, Donlon was appointed the socius, or principal advisor,[12] to the provincial superior of the Maryland Province of the Jesuits.

[14] His style of leadership was one of ample delegation of responsibilities to subordinates and considerable deference to their judgment, some attributing it to his natural passivity and lack of any particular aptitude for the presidency.

[17] Donlon remained as president of Georgetown until May 1, 1918,[11] when he requested the provincial superior to relieve him of the office by a Jesuit with greater vitality.

[15] He led fundraising to permit the purchase of land in the Maryland countryside on which to build the school, and traveled the area to locate such a suitable property.

Having secured the permission of the Jesuit provincial, the President and Directors of Georgetown College purchased 92 acres (37 hectares).

[20][21] On October 25, 1916, ground was broken on the new, Georgian Revival building,[21] with Donlon in attendance and the Apostolic Delegate to the United States, Archbishop Giovanni Bonzano, ceremonially turning the first soil.

[19] In 1905, Donlon was appointed chaplain to the nuns at the nearby Georgetown Visitation Monastery, and held this position until his death.

[11] Donlon was conducting a retreat at Manhattanville College in Tarrytown, New York, on August 31, 1923, when he suddenly suffered a heart attack at 11 a.m. while leaving the chapel.