The 19-year-old is now contracted to Derby until 2018.
Derby County Head Coach Steve McClaren says he's also proud of the fans, who have been 'superb all season'.
Derby County remain in the Championship after Bobby Zamora fired QPR to victory at Wembley. Find out how every player rated out of 10.
Derby County proved they were too strong for Carlisle United, coming out 2-0 winers at Brunton Park in their Capital One Cup first round tie.
Despite controlling large parts of the game, it took a set piece after the hour mark to put Derby ahead - Jeff Hendrick heading in from close range after a corner was flicked on.
Carlisle threatened to come back into it, without really putting Derby goalkeeper Lee Grant under pressure. But the win was sealed by last season's top scorer Chris Martin with a smart volley.
That makes Derby the first side through to the second round in this season's competition.
At half time in tonight's Capital One Cup tie, Carlisle United are holding Derby County to a 0-0 scoreline.
Derby controlled long periods of the game, without troubling the home goalkeeper, Mark Gillespie.
And three big chances after the half-hour mark could easily have put Derby in front, but saves from Gillespie kept two of the attempts out, and Derby's usually-prolific Chris Martin hit the bar in the last minute, when he should have done better.
Derby County have made two changes from Saturday for tonight's Capital One Cup tie against Carlisle United at Brunton Park.
Defender Jake Buxton has been rested after only recently recovering from injury, with former Leicester player Zak Whitbreak taking his place. Winger Jamie Ward also comes in for Johnny Russell.
Derby will also face midfielder Paul Thirlwell, who played at the club for two years from 2005.
Derby County have signed a 21-year-old midfielder from Spanish giants Real Madrid on a season-long loan.
Omar Mascarell was given a guided tour of the club's facilities this morning, before putting pen-to-paper.
He has been used as a holding midfielder for Real Madrid Castilla (Real Madrid's B team), and is described on Real Madrid’s official website as "a thinker, the brain of Castilla. He is a natural organiser and technically gifted".
– Steve McClaren on dcfc.co.uk
We’re delighted that we have been able to bring Omar Mascarell to Derby County on a season-long loan deal.
He is a talented young player and I have monitored his progress for a number of years after first coming to my attention whilst in Holland at Twente.
Our Head of Football Operations Chris Evans has worked tirelessly to get this deal over the line and spent a few days in Spain thrashing out a deal with Real Madrid.
We would like to thank Real Madrid for allowing Omar to spend the season with us and looking forward to working with him.
Derby County midfielder, George Thorne, has posted on social media of his devastation that he will miss up to 9 months of football action with an injury.
Obviously gutted doesn't really cut it, but I know how to handle it. Appreciate all the messages guys
Dont forget what the team achieved last year. Exciting season ahead & I'll join them for the run in. Look forward to seeing the iPro rocking
Derby County have been dealt a huge injury blow as new signing George Thorne has been ruled out of action for up to 9 months.
The 21-year-old only joined Derby last weekend after his transfer from West Bromwich Albion, but got injured during his first pre-season friendly against Zenit St Petersburg on Tuesday.
Scans have confirmed he has injured his Anterior Cruciate Ligament in his left knee, and will have to undergo surgery.
Derby boss, Steve McClaren told the club website:
– Steve McClaren on dcfc.co.uk
At the time it looked to be innocuous as there was no-one near George and we thought he had just jarred his knee...
... It is a huge disappointment for George personally and we wish him a speedy recovery.
His team mates have taken to Twitter to send their best wishes:
Gutted for @georgethorne15 massive loss for us! But know he will bounce back again! Get yourself back for the run in bro x
Gutted for you @georgethorne15 hope the operation goes perfect.
Derby County has confirmed signing of George Thorne from West Bromwich Albion.
The 21-year-old midfielder has joined the club on a four-year deal after an undisclosed fee was agreed with the Baggies.
Thorne was identified as one of Derby’s top transfer targets this summer after he impressed during a loan spell with the Rams last season.
He made 12 appearances in total and scored twice.
Head Coach Steve McClaren, said:
We’re really pleased that George Thorne has joined us on a permanent basis.
I am sure the fans will be delighted to welcome him back and we’re equally pleased that he sees Derby County as the right place for him at this point of his career.
He was one of the first players Ispoke about with our Head of Football Operations Chris Evans when he arrived inNovember, and we were well aware of his qualities when he joined us on loan in January.
After being patient in waiting for his chance in the side, he showed what he could do on the pitch. His level of performance was excellent.
Derby County players Craig Bryson and Johnny Russell have taken to Twitter to express their disappointment after their 90th minute play-off defeat to QPR yesterday.
Gutted we never got the result we deserved yesterday but we will be back! Thanks for all the support over the season ?
This will hurt for a while but we know what we are capable of as a squad! we will be back stronger for it! Fans unreal all year! thank you??
The Rams had managed to avoid a shot on target for the entire game, until Bobby Zamora popped up with the winner at the death.