The singer - who is, at 34, the oldest member of the group - described the decision as "tough" but "necessary".
In a statement on the band's website - backstreetboys.com - he said: "After 13 years of what can only be described as a dream come true, I have decided that it is time to leave the Backstreet Boys.
"It was a very tough decision for me but one that was necessary in order to move on with the next chapter of my life."
He added: "I would like to thank the Backstreet fans for all the beautiful memories we have shared together and look forward to including you in the next phase of my life. I wish my brothers continued success and look forward to their new album."
Richardson's decision to quit came as the remaining members of the band - A.J. McLean, Nick Carter, Howie Dorough, and Brian Littrell - headed into the studio to record their new album.
In a statement they said: "The door will always be open for him to return to the Backstreet Boys. We wish him the all the best in his future endeavors."
Since bursting onto the music scene in the late 90s, Backstreet Boys have sold over 35 million albums and survived a brief break due to A.J.'s stint in rehab.
March 27, 2007 - 01:17PM
kevin why did you quit.i loved you and brian the most you guys were the sexiest and cutest ones i miss you and the backstreet boys singing . il ove you guys
March 27, 2007 - 01:19PM
kevin this is sanaa berro pleses go back
August 21, 2007 - 06:55AM
This is a shock to me!! i really liked you kevin, i never got the chance to see you guys perform, and now i will never see you, kevin perform in the BSB. but always know that i will give support to the BSB to continue with their great music and anything that Kevin
will do in the future. i hope to see yo guys soon in concert, come to england, please. Cant wait, miss you
September 19, 2007 - 01:58PM - Jennie
Oh my god Kevin i cant believe you quit, I love you to death i have all your guys music videos and everysong you put out i love you guys but i like you more (No offense guys) I love you too. But i wish you would come back it's not right, It's just not the same backstreet boys, You were a great singer and i love your music. Please Please come back. Your biggest fan
October 27, 2007 - 04:55AM - christine
hı ı just want to say ı really upset that kevın lıfe th band and he was very good sıng and ı hope he wıll come bk soon ı am bıg fan of backstreet boys ı wıll suppet them wıth song and ı love all song and greater song to and ıt not same wıth out kevın :(
November 16, 2007 - 09:27PM - NanoArg
Hey don't be so crazy little teens, you'll grow up too, and then you will understand that sometimes at some points in someone's life changes are made in order to achieve experience and enrich themselves spiritually by moving on the next stages of life.
Don't worry as i said you'll get over it and in time you'll move on too.
Enjoy .
November 22, 2007 - 01:10PM - LALA
NO! :"-( AH! IM SO INCONSOLABLE! :-( WHERE DID U GO KEV.!??!?! U LEFT UR COUSIN BRIAN ALL ALONE!
November 22, 2007 - 01:15PM - LALA
INCOMPLETE! :-(
December 1, 2007 - 05:52AM - sarah
wean ro7et. ya zam wallah konet mwanesna we back street boys ma beswo balak wallah
December 14, 2007 - 02:32PM - jay torres
dang that sux i remember when u guys came to madison square garden.that was awesome,i still have the vhs tape,lolz.which kinda is wierd.well kevin good luck in w/e ur doing next i doubt u gonna see this its w/e..peace bra.
December 14, 2007 - 02:38PM - Amanda Scott
I want to wish Kevin the best of luck. I was shocked and amazed that Kevin had left. The backstreet boys were my biggest fans back in the day so good luck for the new generation today.
December 14, 2007 - 02:46PM - MAYLIN
i love backstreetboys cd nick carter i'm 1 big fan backstreetboys from maylin miami FL
December 14, 2007 - 03:42PM - Amanda
OMG I can't believe Kevin is leaving. Why Kev?!? I came to see a show of yours in 20. I've been one of your biggest fans for the longest time. It's not going to be the same without you Kevin. But even though I'm not happy about you leaving I will say this, I will support you in no matter what you decide to do. As long as you're happy that's all that matters. And to the rest of the group good luck guys. I wish all of you nothing but the best. I will always support you no matter what. I love you guys! -Amanda
December 28, 2007 - 09:30PM - Felice Headon
IM GUNA MISS U KEV ! IT WONT B THE SAME WITHOUT U. GOOD LUCK FOR THE FUTURE, AND I HOPE TO SEE SUM LIL KEVIN RICHARDSONS AROUND SOON, HEHE :D. ILL ALWAYS SUPPORT THE BACKSTREET BOYS, I HAVE A LOT OF RESPECT FOR YOU ALL. I WISH U THE BEST OF LUCK ! MWAH. PS : IM PROUD OF U AJ FOR CLIMBING THAT STEEP HILL, AND ADMITTING YOU HAD A PROBLEM. I LOVE YOU, IL SEE U WHEN U COME TO AUSTRALIA :D HOPE TO SEE SOME FLESH :D HA
January 7, 2008 - 11:44PM - tasha
TELL ME WHYE!
February 2, 2008 - 09:38PM - taylor
why do you have to leave kevin? i will really miss you
February 14, 2008 - 08:30PM - clare
hi kev tel me why? u leave the band. when i am watch inconsolable i cal al my friends and ask were is kev u wil be miss anyhere u already now what love u bad
February 20, 2008 - 05:11AM - ana luiza
oi lindo
February 28, 2008 - 03:45PM - Brenda
Aw Kevin. We love you! You should totally come back.
March 6, 2008 - 09:29PM - Richard
Kevin, can we see you all 5 together again? The Backstreet has been ruined by other singers. Can you remember the times that you all 5 spent together?
March 8, 2008 - 01:09PM - angelica
a mi me gustan muchisimo los cinco por que son a todo dar cuando dan sus entrevistas por eso los amo y son los mejores de todo el mundo los numero uno no hay comparacion con nadie ante ustedes los amo y no se olviden de sus fans que los amamaos un buen
angelica de mexico df..
March 19, 2008 - 07:08AM - natalia
a mi me entanta lsa 5 susu boses armoniosas q tieneen cuando los escucho es como si estubiera en las nubes soy super fanatica de kevin tebgo un monton de fotos de el es super lindo y sexy aunque el mas biejo es el mejor de todos es unico al igual q aj tambien es super lindo y canta como nadie.
no menos de los demas tambien es super lindo brian se podria decir que es el q mejor canta .
nick y gual pero q no le ponga tanto color cuando canta de veras no se le ve bien.
and hewi tambien tiene el cuero no hay nada q decir es el q mejor baila junto a kevin cuando bailan los dos se lusen.ya xaus no joteo mas chabela y q vivan los backstreet boys son lo mejor de lo mejor mejor q nsunc. s clab 7 space girls lo mejor son ello s the backstreet boys.:)
viva la musica
bamos backstreet boys son los mejores
March 22, 2008 - 06:25PM - kayla d'etta
Kevin,it is very surprising to see the Backstreetboys with out you.Good luck to you. YOU ARE AWESOME
April 4, 2008 - 11:31AM - reza
kevin,i had destroyed me with this ,just this!the best wishe for u.
April 19, 2008 - 03:01AM - Lidiya
Kevin! We support you and Boys! But we still hope that you'll come back!
April 19, 2008 - 10:06AM - Amanda B.
So Kev, the Boys aren't quite the same without you but they are doing very well. I know a lot of us fans were shocked when we found out you were leaving but we all know it was for the best and that you had other plans that you wanted to see through. Congrats to you and Kristin on a beautiful baby boy last summer and we hope to see you out soon!!
April 19, 2008 - 02:37PM - Catie
Kevin, we will miss you but you are never forgotten! I wish you only the best and hope you and your family have a wounderfu time together! :) Thank you for the great memories!
April 28, 2008 - 03:59AM - Rudra
it is so nice of da backstreet boys 2 keep the door open for him..we really appreciate it.we will miss u kevin..a lot.plz come bak as soon as possible,please.we love u.n also the other boys.kevin.please cm bak.congatulations 2 the boys 4 their superb album-UNBREAKABLE.it is js so awesum.actually all of dem r rockin.i lv all of their songs esp. quit playn games.
May 3, 2008 - 02:08AM - Lily
Good luck!
August 30, 2009 - 01:32PM - Jolly
I am still a diehard fan of the Backstreet Boys no matter what. But I wish Kevin will go back and sing again with his group. Cheers!
August 30, 2009 - 01:36PM - Jolly
. and i feel that Kevin will be back, I am positive! Cheers for Kevin coming back with the group. I keep on praying! Cheers in advance!
September 18, 2009 - 05:45PM
tell me the reason
September 18, 2009 - 05:46PM
Hey Kevin this is Jason i will always love you and the loving we both sheared with each other love you daddy
October 19, 2009 - 02:22PM - Anonimo
Kevin a hecho las cosas muy mal. Ha demostrado lo poco que le importan sus fans y además le ha dado iguál lo que sintiese el resto de la banda. Su objetivo a sido ganar dinero y hacerse famoso, una vez conseguido, se ha casado con su novia de toda la vida (encima embustero el núnca reconoció tener pareja) y después no le digas náda porque encima responde que es su vida. Si, claro, pero bién que no ha su "noviecita" la que a estado esperando o gastando dinero para su disco o para verlo en un concierto, verdad? VAYA MIERDA.
November 12, 2009 - 11:37AM - Andy
Backstreet Boys will never be the same once Kevin left(he was the Best looking of all the Boys)The fact that Kevin was older is why I think he will be missed the most because he held the goroup together,kind of like the Dad of the group.I hope Kevin can have a solo career,I dont feel BSB gave him a enough chance to sing on his own.I wish you the Best Kevin and hope your leaving wasnt based on health issues,just your time to move on.God Bless.
November 21, 2009 - 01:16AM
Your stupid for leaving kevin the backstreet boys will never be the same i dont even listen to them anymore after you left
