James Tate and two friends who helped him received one-day suspensions from Shelton High. Under the previous rules, everyone suspended after April 1 was barred from the prom.
Beth Smith, the school's principal, announced a change in policy, The Hartford Courant reported. There will be alternative penalties instead of the prom ban.
Tate became a hero in Shelton and elsewhere; his local admirers include Shelton School Superintendent Freeman Burr, the newspaper said.
"For us gentlemen, James Tate has set a new level of romanticism," Burr said. "Principals have to make difficult decisions every day. No one could have anticipated this kind of response."
A Facebook page dedicated to supporting his bid to go to the prom has 196,000 fans.
Tate had a simple message in individual letters: "Sonali Rodrigues, will you go to the prom with me? HMU [Hit me up] -- Tate." The school said his action was a safety violation, although he said he wore a helmet and had one friend hold the ladder while the other put tape on the letters.