The actor, who played Kyle Slater on the soap from 2015 to 2016, looked almost unrecognisable in the new snap as he flexed his muscles.
Riley shared a side by side before and after shot and posted an inspirational message encouraging people to keep going with their own fitness journeys.
Wow: Former EastEnders star Riley Carter Millington has unveiled his dramatic weight loss transformation
He wrote: ‘Don’t say you can’t change. Because you can. It can take time but you will get there. I’m still on my journey but loving me more each day.’
The actor sported an array of arm tattoos in the snap while he now also has platinum blond hair.
Riley was inundated with positive messages from his followers while some of his former EastEnders co-stars also praised him for his efforts.
Lisa Hammond, who played Donna Yates on the soap, wrote: ‘I think u r a marvellous human Riley I don’t love u less or more in ‘before or after’ pic’s u share (for me personally) tbh.
Transformation: The actor, who played Kyle Slater on the soap from 2015 to 2016, looked almost unrecognisable in the new snap as he flexed his muscles
‘I encourage whatever we all need to do to make ourselves feel good & powerful in a safe and healthy way. All strength to you my friend, loads of love xx’.
Luisa-Bradshaw White, who plays Tina Carter wrote: ‘HOT!!!!’ while Hollyoaks actress Amanda Clapham wrote: ‘You look great Riley!’
When he joined EastEnders in 2015, Riley became the first transgender actor to play a regular transgender character in British soap history.
Reaction: Riley was inundated with messages from people congratulating him, including some of his former EastEnders co-stars like Lisa Hammond and Luisa Bradshaw-White
When he first joined the soap, the actor said in a statement: ‘I am extremely excited to be joining EastEnders.
‘I can honestly say that I have now fulfilled my two biggest dreams – to be living my life as a man and to be an actor.
‘I cannot wait to really get stuck in with filming and I look forward to seeing what is in store for my character.’
Big moment: When he joined EastEnders in 2015, Riley became the first transgender actor to play a regular transgender character in British soap history
Riley left the show in 2016 after producers were said to have believed his character storyline had ‘reached a natural end’.
Speaking to Metro.co.uk, Riley said: ‘When I landed a six-month contract at EastEnders it was a dream come true. For that to be extended to a year was something I never expected.’
‘As the time comes for Kyle to depart Walford I am looking forward to taking on new roles and who knows, Kyle may find his way back to Walford one day.’
Departure: Riley left the show in 2016 after producers were said to have believed his character storyline had ‘reached a natural end’
Source: Daily Mail