The 20-year-old winger has joined the Championship newboys, who finished second in League One last term, in a deal believed to be worth around £1.2million (Derby Telegraph), subject to EFL approval.
Thomas began his career with Cheltenham Town before moving to the Rams in 2016, rising through the East Midlands club's ranks and going on to make two senior appearances (Transfermarkt).
He made his debut as a late substitute in a 2-0 win against Queens Park Rangers at Pride Park Stadium in November 2017, which was then followed by another appearance off the bench, in April 2018 at home to Bolton Wanderers (official Derby website).
Thomas spent the 2018-19 season on loan at League One side Coventry City, a fruitful stint in which he scored five times in 44 appearances.
Here is what Thomas posted on Twitter to Derby and their fans following his switch:
Some Rams fans - plus ex-teammate Craig Bryson - took to the social media platform to reply and wish him all the best:
All the best boss— Craig Bryson (@cbryson44) 13 June 2019
Good luck Luke— D C F C (@DCFC101) 13 June 2019
Wish you could’ve stayed— (@_FtblConor) 13 June 2019
Best wishes for the future, Luke— Tony Luke (@TonyRamsRev) 13 June 2019
Good luck— Alastair (@AlastairRichar5) 13 June 2019
Good luck fella I would have loved to see you play for us next year— gavin isham (@gavinisham1) 13 June 2019
Great young player. Can't understand why Derby are letting you go. Once a Ram...— Julie Messenger (@JulieMessenger) 14 June 2019
Good luck kid, don’t try too hard when you come to Pride Park— Ollie (@Wileman_Oliver) 13 June 2019
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