Digital download available now, CD single out on 15 December.
It's back to big ballads for the X-Factor sweetheart, with Leona creating her own version of Snow Patrol's weepy hit.
Cover versions can sometimes just be a lesser version, but this slow-rock love song has been completely revamped!
The full gospel choir and orchestra easily match Leona's powerful pipes - and remind listeners why the song made people cry when she first performed it on Radio 1's Live Lounge last year.
Leona gets every last ounce of emotion from the Snow Patrol lyrics - but she's not entirely clear where she's running, or who she's running with!
It seems she has to say goodbye to someone she loves, but that if she had the choice, they'd run away - together.
But wherever she's running, there IS a light at the end of the tunnel:
"Light up, light up, as if you have a choice, even if you cannot hear my voice, I'll be right beside you dear."
Will you still be humming it next week?
Well, we've been humming it for a year already - so what's another week?!
It's already top of both the iTunes and Irish charts - so it's not really a question of how high it goes but how long it stays there.
Will it make the charts?
With Run available to buy on CD single from December 15, you can't help but wonder if Leona's after the ultimate chart success
A UK Christmas number one? Maybe, this tune certainly has the X(mas) factor!
This reviews page is now closed. Here are some of the reviews you sent in.
"Amazing!!!! I love all of her songs but this is the best by far!!!"
Lydia, 13, Birmingham, England
"I love it, but it isn't as good as Bleeding Love, which is still her best song."
Merryn, 12, Birmingham, England
"I think Leona is amazing. Run is a perfect song for her voice! I can't stop listening to it - I definitely recommend it to anyone who has not yet listened to it!"
Leila, 11, West Sussex, England
"I think it's great. I have her album and I listen to this song all the time."
"I love Leona! She was born to do this. This song is OK so I was a bit disappointed. Hopefully her next number one will be better."
Jessica, 10, Wiltshire, England
"I love it, it's been stuck in my head for this week as it's one of my fave ones. I'm lucky as I got it as a Christmas present so now I can listen to it all day long."
Tallulah, 12, UK
"I love this song; it is way better than the original."
Katie, 12, London, England
"I think she has ruined the song as the original version was a lot better."
Aimee, 12, Yeovil, England
"Wow, Leona Lewis' Run is outstanding. I love her voice as it really matches the song. I think her version is better than Snow Patrol's, but they are fab for making it up!"
Natalie, 10, Lancashire, England
"I love this song! Leona sings every word of Run with so much emotion and passion. I really must download this!"
Amy, 12, Derby, England
"Normally I'm not into this type of music but when I heard this song I loved it."
"I really like this song; it's groovy and it's a perfect chilling out song."
Keeley, 10, Rotherham, England
"It's absolutely fantastic!!!!! I loved it when I first heard it and I haven't stopped humming it since!"
Miranda, 12, Worthing, England
"I think Leona murdered a perfectly good song. I much preferred the Snow Patrol version. In this song you can't understand a word she's saying!"
Megan, 11, Llandudno, Wales
"It's great, but all her other songs stink. And Snow Patrol's version is better."
Gary, 12, Liverpool, England
"Amazing song - the music video is beautiful! Leona has a stunning voice!"
Jen, 14, UK
"This isn't Leona's best song but it is still absolutely fab. I looked up the words and I know them all already."
Katie, 9, Glasgow, Scotland
"I love this song! I think it really suits her voice."
Petra, 11, Belfast, Northern Ireland
"This song is brilliant!! I have loved every single song of hers since she won the X Factor, and this is no exception."
Connor, 11, London, England
"This song is amazing - she's amazing! Leona deserved to win the X Factor. Go Leona Lewis!"
Holly, 11, Northampton, England
"I love this song! It's so sad and I think it's really soft and nice. Definitely one of the best songs of 08!!!"
Megan, 11, Warrington, England
"I hate X Factor so I don't really know much about Leona Lewis. I have one of her songs which is quite good. I don't see why such a big fuss should be made over one silly little song! It's ridiculous in my opinion!"
Ellie, 9, Surrey, England
"Run by Leona rocks! Must download it."
Nick, 11, Norwich, England
"I think the song is beautiful, and Leona's version is outstanding. The emotion and strength is just overwhelming. True talent."
Steph, 14, Liverpool, England
"If I was in Snow Patrol, I'd be very proud! It is such an emotional song and Leona makes every song worthwhile."
Emily, 11, UK
"I don't think that it suits her vocals. Many people WILL disagree with me - but I much prefer the original."
Emily, 12, Poole, England
"Leona Lewis is great no matter what she sings. This song is brilliant and you can really feel the emotion. The end of the song is so uplifting and she can reach all the high notes."
Zakiyyah, 15, Walsall, England
"I love the song, it is fantastic. It's going to be a great hit for Leona."
Laura, 10, Merseyside, England
"The song is so good, but Leona can do better."
Martin, 12, Gillingham, England
"I think its OK! The chorus is good but in some places it can be really boring."
Izzy, 11, Oxfordshire, England
"I love this song, she can sing it better than Snow Patrol."
Grace, 10, Preston, England
"Although Run is definitely Leona's best yet, I can't help but find her voice a little whiney."
Rosie, 11, Poole, England
"I find this song quite boring, but she makes me love it!! Her voice is amazing! No matter what the song is!"
Emily-Jayne, 12, Cornwall, England
"I can't understand a single word she says, but it is an amazing song!"
Adam, 12, Birmingham, England
"It is the best Leona Lewis song I have heard yet. YOU'RE THE BEST LEONA LEWIS."
Kyrsty, 9, Birmingham, England
"It is great! :) Leona's voice is outstanding. Keep up the good work."
Kate, 8, West Sussex, England
"Video's a bit cheesy, but it's still fab!"
Ami, 14, Glamorgan, Wales
"It's a rubbish song! I'm disappointed in Leona."
Zarghona, 9, Barnsley, England
"It is a beautiful song and I think it will definitely take the top spot in the singles chart."
Hattie, 11, Warwickshire, England
"I hope her new song Run goes to number 1, it is so good. I actually think that it is better than Snow Patrol's version; and they wrote the song!"
Sadiya, 13, Bradford, England