The former 'American Idol' runner-up will appear in the upcoming fifth season of the TV musical, which takes place in a high school, reported E! online.
'Glee' co-creator Ryan Murphy confirmed the news on Twitter.
"I am thrilled to announce that the super talented Adam Lambert is joining the cast of Glee this fall."
Murphy did not reveal what part Lambert will play.
The pop star has previously voiced his appreciation for the show and said he would love to play himself in the singing series.
Lambert isn't the first former 'American Idol' contestant to appear on 'Glee'.
Last year's runner-up Jessica Sanchez had a guest role as a rival singer from another school.