Gran Alegria began her second campaign in the Grade 1 Oka Sho over 2000 metres at Hanshin on 6 April in which she started the 2.4/1 second favourite behind Danon Fantasy. The other sixteen runners included Chrono Genesis (Daily Hai Queen Cup) as well as No One and Pourville who had run a dead-heat in the Fillies' Revue). After racing in fourth behind the front-running Pourville, Gran Alegria took the lead entering the straight, broke clear of the field and came home two and a half lengths clear of Shigeru Pink Dia. Her winning time of 1:32.7 broke the race record set by Almond Eye in 2018. Christophe Lemaire commented "She certainly won strongly today. I was a little bit worried as it was her first time out after a long break. She was unable to make use of her speed in the Asahi Hai Futurity so I made sure this time to secure a good position early on and from there I had every confidence in her exceptional speed." On 5 May Gran Alegria was matched against colts again when she was dropped back in distance for the NHK Mile Cup over 1600 metres at Tokyo and started the odds-on favourite. After tracking the leaders she kept on the straight but was unable to quicken in the closing stages and came home fourth behind Admire Mars. She was subsequently relegated to fifth for causing interference. The filly did not return to the track until 21 December when she was matched against older horses in the 1400 metre Hanshin Cup and started the 1.1/1 favourite. Lemaire settled Gran Alegria in mid-division before moving to the front 200 metres from the finish and pulling clear to win by five lengths from the five-year-old Fiano Romano. In January 2020, at the JRA Awards for 2019, Gran Alegria took the JRA Award for Best Three-Year-Old Filly, taking 121 of the 274 votes to win from Loves Only You and Chrono Genesis.