Posting a series of behind-the-scenes photos, Clarke - who plays Daenerys Targaryen in the HBO fantasy series - wrote: "Finding the words to write this post has left me overwhelmed with how much I want to say but how small words feel in comparison to what this show and Dany have meant to me.
"The mother of dragons chapter has taken up the whole of my adult life. This woman has taken up the whole of my heart.
"I've sweated in the blaze of dragon fire, shed many tears at those who left our family early, and wrung my brain dry trying to do Khaleesi and the masterful words, actions (and names) I was given, justice.
"Game of Thrones has shaped me as a woman, as an actor and as a human being. I just wish my darling dad was here now to see how far we've flown.
"But to you, dear kind magical fans, I owe you so much thanks, for your steady gaze at what we've made and what I've done with a character that was already in the hearts of many before I slipped on the platinum wig of dreams. Without you there is no us.
"And now our watch has ended."
Her fellow Game of Thrones alumnus, John Bradley-West - who plays Sam Tarly - commented on Clarke's post, simply writing: "Beautiful."
Over on his Instagram profile, meanwhile, he shared a photo of his rehearsal and prep schedule from his season one days, writing: "So tonight we have our very last episode. It's the final step of a long and wonderful journey. A journey that, for me, started at 10am on Monday 19th of July 2010.
"I know this because recently I found my rehearsal and prep schedule for season 1, week 1. This was given to me when I landed in Belfast for the first time, weeks before we even started shooting.
"Listed here is the rehearsal where I first met Kit, and the first time I wore the costume that's seen me through 8 seasons.
"I'm glad I kept this. I met so many people that week who have come to mean so much to me. Back then we couldn't have known the journey we'd go on together. I wouldn't swap that experience, or those people, for the world.
"Enjoy the episode and thanks for everything."
Something tells me this is gonna be an emotional one, folks. Get strapped in.
Game of Thrones concludes on Sky Atlantic at 2am on Monday 20 May, then repeats in the UK and Ireland at 9pm that same day.Featured Image Credit: Instagram