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.
"Glee" paid tribute to Monteith and his character, Finn Hudson, last year. The show will return midseason for a final 13-episode run.