On June 26, 2011, Juniel was the opening act in Oh Won Bin's live tour "Good For You", at Akasaka BLITZ. She later went on to be the opening act in F.T. Island's "2011 Summer Tour - Messenger" in Tokyo. On July 12, 2011, Juniel released her second mini album "Dream & Hope". After her second mini album, Juniel underwent a label change to Warner Music Japan and made her debut under Warner Music Japan with the single "Forever". On December 24, 2011 Juniel to be the opening act in “Lawson Presents Music For All All For One Supported by Skapa!” at Yoyogi National Stadium First Gymnasium.
On February 15, 2012, Juniel released her second Japanese single, "Sakura ~todokanu omoi~". On May 22nd, Juniel debut in South Korea. She released “Fool” with CN Blue Jung Yonghwa off of her first mini album ‘My First June‘. CN BLUE Yonghwa was produce this song for Juniel. To support his fellow artist, Yonghwa has stepped up not only as a producer but as an actor in her music video as well. On June 7, 2012, her official debut single, "illa illa", was released. She held her debut showcase and released her full mini album 'My First June' on the same day.