Michele, Monteith's on- and off-screen girlfriend, posted pictures and paid tribute to him on Sunday.
"We hold you in our hearts today, and every day we remember your smile. We will love you and miss you always," she wrote.
Other "Glee" cast members including Matthew Morrison, Amber Riley, Kevin McHale and Ryan Murphy also posted tributes to their late co-star.
We hold you in our hearts today, and every day we remember your smile. We will love you and miss you always. ❤️ pic.twitter.com/deA4PQUZNz— Lea Michele (@msleamichele) July 13, 2014
Miss you pic.twitter.com/e89rS8lENB— Ryan Murphy (@MrRPMurphy) July 13, 2014
I remember your smile and your warm hugs! 1 year without you and your presence is still felt. Miss and love u everyday big bro 💜 Our Angel— Amber Patrice Riley (@MsAmberPRiley) July 13, 2014
I personally believe Cory was reborn into some other beautiful form a year ago today. I celebrate him and his life... Wherever that may be.— Matthew Morrison (@Matt_Morrison) July 13, 2014
love ya bro— Mark Salling (@MarkSalling) July 13, 2014
I miss him terribly. I know you all miss him too. To Cory... pic.twitter.com/tfwHKE0gXv— Dianna Agron (@DiannaAgron) July 13, 2014
It's been 1 whole year & it's still so surreal, but today is just a reminder of how damn great you were and how much you mean to us all. ❤️— Kevin McHale (@druidDUDE) July 13, 2014
I often think of the good memories I shared with Cory and it makes me smile. He was a one of a kind gentleman and will forever be missed.— Harry Shum Jr (@HarryShumJr) July 13, 2014
One year later and I miss Cory everyday. I hope we make him proud.— Lauren Potter (@TheLaurenPotter) July 13, 2014
AWW TODAY IS A TOUGH DAY! BUT I HOLD IN MY HEART SO MANY BEAUTIFUL & FUN MEMORIES! MISS & LOVE THIS MAN/BOY!🏈😘LOVE U pic.twitter.com/S9SNB8goQg— Dot-Marie Jones (@dotmariejones) July 13, 2014
A YEAR..I WILL ALWAYS HOLD DEAR THE AMAZING TIME I HAD WITH CORY! AS WE MOVE ON IN LIFE I KNOW HE IS MOVING ON IN A BEAUTIFUL PLACE!😊😘— Dot-Marie Jones (@dotmariejones) July 13, 2014
I miss you Cory, I think about you everyday.— samuel larsen (@SamuelLarsen) July 13, 2014
"Glee" paid tribute to Monteith and his character, Finn Hudson, last year. The show will return midseason for a final 13-episode run.