Kurtz officially signed a National Letter of Intent after committing to play for the Cougars on Aug. 11, as reported by the Deseret News' Brandon Gurney.
Shelton, who signed as a midyear enrollee, also committed to play for BYU this summer, just a few weeks before Kurtz.
Both players will enroll in school in January.
"Nick and Michael are both great athletes and excellent football players,” BYU coach Bronco Mendenhall said in the school's news release. “We look forward to having them join our program in January.”
The 6-foot-6, 205-pound Kurtz will come to BYU as a junior with three years to complete two years of eligibility. In 18 games at Grossmont College, Kurtz had 1,301 receiving yards and 18 touchdowns, as well as six multi-touchdown games.
The 5-foot-8, 170-pound Shelton played both offense and defense for Wakefield High School in Raleigh, N.C. Shelton, who has clocked a 4.43 time in the 40-yard dash, had a team-high three interceptions in 2013 and added 20 receptions for 277 yards in helping his team finish with an 11-2 record.