Pada 5 November 2014, debut Lovelyz pertama kali diumumkan oleh Woolim Entertainment.<ref>{{Cite news|url = http://www.newspim.com/view.jsp?newsId=20141103000080&fromurl=na|title = 울림 첫 걸그룹 ′러블리즈′ 데뷔 임박, 10일 음원 선공개로 ′출사표′|last = Yang|first = Jinyeong|date = 2014-11-03|work = |access-date = |via = }}</ref> Sebelum resmi debut, Seo Jisoo mundurdiumumkan tidak akan berpartisipasi dalam promosi debut karena alasan pribadi.<ref>{{cite web|url=http://www.kpopstarz.com/articles/135158/20141112/seo-ji-soo-will-not-attend-lovelyz-debut-promotions-due-to-shock.htm|title=Seo Jisoo Reportedly Will Not Attend Lovelyz Debut Promotions Due To Shock|work=KpopStarz}}</ref> Pada 10 November, Lovelyz merilis singel digital "Good Night Like Yesterday". Showcase debut mereka digelar pada 12 November di K-ART Hall Olympic Park, mereka melakukan debut pada hari berikutnya di ''[[M! Countdown]]''.<ref>{{cite news|last1=Hong|first1=Grace Danbi|title=Lovelyz Wishes You a ‘Good Night Like Yesterday’ in Debut MV|url=http://mwave.interest.me/enewsworld/en/article/80323/video-lovelyz-wishes-you-a-good-night-like-yesterday-in-debut-mv|accessdate=November 25, 2014|work=[[CJ E&M]] enewsWorld|date=November 10, 2014|archive-date=2014-11-22|archive-url=https://web.archive.org/web/20141122181207/http://mwave.interest.me/enewsworld/en/article/80323/video-lovelyz-wishes-you-a-good-night-like-yesterday-in-debut-mv|dead-url=yes}}</ref> Album debut mereka, ''[[Girls' Invasion]]'' dengan singel utama "Candy Jelly Love", dirilis pada 17 November.<ref>{{cite web|title = Lovelyz drops debut album amid controversy|url = http://www.koreaherald.com/view.php?ud=20141117000884}}</ref> Album ini menduduki posisi kesembilan di tangga lagu mingguan Five Music Korea-Japan Taiwan dan posisi pertama pada tangga lagu album Tower Records Jepang.<ref>{{cite web|title=Newly Debuted Girl Group Lovelyz Crack The Top 10 On Taiwan's Five Music Chart|url=http://www.kpopstarz.com/articles/141918/20141125/newly-debuted-girl-group-lovelyz-crack-the-top-10-on-taiwans-five-music-chart.htm|website=KpopStarz|accessdate=8 July 2015}}</ref>
[[Berkas:14.12.21 SAF 러블리즈 축하무대.jpg|jmpl|215px|ka|Lovelyz pada acara SBS Gayo Daejun]]
