This has been an emotionally intense year for the poet and fiction writer Ocean Vuong.

In June, his first novel, “On Earth We’re Briefly Gorgeous,” written as a Vietnamese immigrant son’s letter to his illiterate mother, came out to much fanfare. Not long before publication, Mr. Vuong’s own mother learned she had Stage 4 breast cancer.

Then, earlier this month, he was back from his book tour, and looking forward to the steadying routines of teaching at the University of Massachusetts at Amherst, when he got a phone call delivering some startling news.

“I had to make sure they had the right person, because you don’t want to cry and then have them say it was a mistake,” he recalled. “But then the tears came.”

Mr. Vuong, 30, is one of 26 people chosen as 2019 fellows of the John D. and Catherine T. MacArthur Foundation. Known colloquially as the “genius” grant (to the annoyance of the foundation), the fellowship honors “extraordinary originality” and comes with a no-strings-attached grant of $625,000, to be distributed over five years .