|Country||United Kingdom and Ireland|
|Broadcast area||United Kingdom and Ireland|
|Picture format||1080i HDTV|
(downscaled to 576i for the SDTV feed)
|Timeshift service||Nick Jr. +1|
|Owner||(ViacomCBS Networks UK & Australia/Sky Group)|
Nick Jr. Too/Nick Jr. 2
|Launched||1993 (programming block)|
1 September 1999 (TV channel)
24 April 2006 (Nick Jr. 2)
|Virgin Media||Channel 715|
Channel 716 (Too/Nick Jr. 2)
|Virgin Media Ireland||Channel 607|
|Sky (UK)||Channel 606 (HD)|
Channel 613 (Too/Nick Jr. 2)
Channel 622 (+1)
Channel 645 (SD)
|Sky (Ireland)||Channel 606|
Channel 622 (+1)
Channel 625 (HD)
|TalkTalk Plus TV||Channel 484|
|BT (via Now TV)||Channel 470|
Channel 476 (HD)
Channel 490 (Too/Nick Jr. 2)
Channel 490 (Too/Nick Jr. 2)
|Eir Vision||Channel 615|
|Sky Go||Watch live (UK & Ireland only)|
|Now TV||Watch live (UK only)|
|TVPlayer||Watch live (UK only, TVPlayer Plus subscription required)|
|Virgin TV Anywhere||Watch live (UK only)|
Nick Jr. was first broadcast in the UK and Ireland from 1993, during the daytime hours from 9am to 12pm on Nickelodeon. By 1998 it broadcast between 10am to 2:30pm.
When it first properly aired it was presented by Face, which he presented the UK-input from 1995 until September 2005, and was being voiced by David Holt.
Nick Jr. was spun off into its own channel in 1999, although the slot on Nickelodeon continued until July 2000, initially broadcasting on Sky, and from 6am to 10am alongside Sky Sports 3 on analogue satellite, although this schedule would sometimes be altered if sports were being covered in the early morning. However, on digital platforms, Nick Jr. aired from 6am to 8pm. At closedown, it would air a short closedown bumper featuring some characters from Nick Jr. shows and an announcement telling viewers to resume watching at 6am, before cutting to a static screen with the characters and the broadcast times until 6am the next morning.
In 2001, MTV Dance started broadcasting during its downtime hours after it was spun off from MTV Extra. MTV Dance acquired its own separate channel in 2002 and both MTV Dance and MTV Extra have since extended their broadcasting hours.
On the 4th of February 2002, Nick Jr. rebranded into a simple, and similar but different style to the American branding used at that time. It had a specific jingle, and the idents usually consisted of children playing around or dancing.  On some occasions, they would broadcast these atmospheric idents which included babies. Sometimes these idents would take up half the ad breaks, or sometimes they appeared in split-screen graphics and next bumpers.  What also came with this rebrand were promo endboards. Dora The Explorer and The Hoobs had its premieres the same day of the rebrand.
In Autumn 2002, they updated their DOG to a much cleaner, organised and less opaque state.
On 31 May 2004, Noggin launched as a block showing classic British children's TV programs from 8pm to 10pm, therefore extending broadcast hours to 10pm. After Noggin finished airing, it would cut to a variation of the static closedown board.
In July 2004, some in-vision morning presenters were introduced to the network. Neal Wright (Zak) and Jennifer Johnston (Jen) presented and hosted this block simply called "The Garden." Alongside them, there was a puppet-plant called Bud, and a blue ball of light / firefly named Izzy. They were dropped in late 2005. 
Also around this period in 2004, Nick Jr. started to use the 2D American animal idents originally introduced there in 2003. It is unknown to when they stopped showing them. 
Around the same period in 2004, Nick Jr. reeled in the new look of Face to their channel introduced in America the year prior, usually referred to as "Modern Face". He was also voiced by David Holt, just like original Face. Nick Jr. made a farfetched decision to not drop the original Face during this occasion, so in the time period this was happening, Modern Face and Face's old look were both broadcast at the same time, confusing the viewers who watched the channel. The UK-dubbed version of Modern Face is extremely hard to come across. 
Around the time of Spring 2005, a new animated presenter appeared on the channel alongside Face at the time. This was Piper O'Possum, which she presented for the UK-input of Nick Jr. until its rebrand on April 30 2010. She was voiced by Alex Kelly in the UK-input and lasted a way more ordeal time than the mascots' time in America. When the September 2005 rebrand happened, she was the main presenter for most of the day, but in the late afternoons she got taken off for the rest of the remaining hours and her segments of announcing shows usually got replaced with normal next bumpers. Before the 2005 rebrand, a confusing mix of her, Old Face and Modern Face all allegedly presented the channel at the same time, making it even more confusing than before she was introduced.
During the rebrand on 5 September 2005, Face was completely dropped instead of presenting alongside Piper O'Possum. In addition, Noggin was renamed to Nick Jr. Classics and the ident package that had been used since 2002 was dropped, as the international versions of Nick Jr. launched a 2D-3D animated pop-up-book-style ident package, with two animals (a parent and a child) forming the Nick Jr. logo, very similar to the package of Nick Jr. on CBS from 2004 to 2006. This package was designed by British animation studio Studio AKA. The Backyardigans had its linear UK premiere the same day of the rebrand.
This package would be used on its then-new sister channel Nick Jr. 2 and on the main Nick Jr. channel until April 2010. Before Nick Jr. Classics, both channels showed a sign off ident telling viewers to come back at 6am, and after Nick Jr Classics, cut to a night loop of the same ident playing over again.
A version of Nick Jr. for Ireland was launched in 2006. This version, like the Irish version of Nickelodeon, shares the same schedule as the British version of Nickelodeon, but has Irish adverts.
Following the removal of Nick Jr. Classics from the main Nick Jr. channel, it extended its broadcast hours to 6am to 10pm.
On 30 April 2010, Nick Jr. updated and rebranded to a prototype of the United States look. They used the American idents along with their own which included still shots of children in assorted places or doing things like letting go of a balloon, or being at a picnic. Their branding in general had a different feel to the original American graphics, but it was the same gist. In addition, Nick Jr. Classics was removed from the lineup, but the shows still aired for a while after that. Nick Jr. started broadcasting 24/7 on 23 August 2010, and has broadcast since then for 24 hours a day.
In July 2016, Nick Jr. HD launched on Sky, replacing MTV Live HD's Sky slot.
Another channel, Nick Jr. 2, was launched on 24 April 2006. When it launched, the idents and branding was just the same as the main channel. The differences were that logos on promo endboards and promos in general had a 2 included next to them. This also was used in the next bumpers and general idents. Nick Jr. 2 was initially supposed to work like a +1 channel, but later reran old shows that the main channel didn't air like I Spy or Sali Mali. Later on, it started to air shows exclusive to the channel. An example of this is It's A Big Big World. It was renamed to Nick Jr. Too in November 2014.
Since October 2013, the channel has occasionally aired long-term marathons (usually one month) of the British preschool series Peppa Pig, during which it rebrands itself as Nick Jr. Peppa. The channel has since broadcast marathons of the Canadian preschool series PAW Patrol in a similar manner, likewise rebranding as Nick Jr. PAW Patrol.
During the mid and late 2000s, Nick Jr. and Nick Jr. 2 presented a nighttime programming block dedicated to classic British children's programmes from the 1970s and 1980s under the title Nick Jr. Classics. The block launched under the name Noggin on 31 May 2004, running every night from 8:00 p.m. until 10:00 p.m. It was rebranded as Nick Jr. Classics on 5 September 2005.
The block was discontinued on Nick Jr. on 4 January 2009 and on Nick Jr. 2 in mid-late 2010.