The UK Championship was the main competition of the UK series of Robot Wars, primarily featuring heavyweight competitor robots and held to determine the national champion of the United Kingdom. Ten UK Championships have been held across both of the show's runs so far - seven in the original series, and three since the show's reboot in 2016. Most main series of Robot Wars used different formats, with the amount and structure of Heats and number of robots in each heat varying between each series, with the exception of Series 8 and Series 9.
Since Robot Wars entered its original hiatus, the FRA-sanctioned UK Championships have continued to run as part of live events hosted by Roaming Robots (until its adoption of the Robot Wars brand name between 2013-2016) and Robots Live!.
- Main article: Robot Wars: The First Wars
The first series only featured six Heats due to how few contestants were avaliable. All six Heats had six competing robots. The first round of each Heat was The Gauntlet, an obstacle course which every robot had to try and complete, with the worst performing robot being eliminated. The second round was The Trial, a small event, such as British Bulldog or Sumo. The five remaining robots would compete, and again the poorest performing robot would be eliminated.
The third round was The Arena. The four remaining robots were separated into two one-on-one battles, with the winners going through to the Heat Final. The Heat Final was another one-on-one battle, with the winner going through to the Grand Final.
The Grand Final was not a separate episode like the other series, but one battle at the end of the sixth Heat. All the robots fought at once, with no breaks (unlike an Annihilator), with the last surviving robot being declared champion.
- Main article: Robot Wars: The Second Wars
The format of the series changed dramatically in Series 2. The amount of heats doubled, and there were now two Semi-Finals, and the Grand Final was a separate episode. However, the format of each heat stayed the same, and the Semi-Finals followed a similar format, with the Gauntlet as the first round of the Semi-Final, followed by a Trial stage, before the Arena stage. The two robots who won their fights went through to the Grand Final.
The Grand Final consisted of two one-on-one eliminators, before the final battle to decide the champion. The losers of each eliminator would fight each other for 3rd place before the final battle. This format that was used for the Grand Final was continued for every series that followed during the show's original run.
- Main article: Robot Wars: The Third Wars
Series 3 featured a complete change to the format. Most notably, the Gauntlet and Trial stages were scrapped, in favour of it being entirely combat based. The amount of heats increased to 16, with there now being eight robots in each heat. There were four one-on-one Round 1 battles, before having two heat semi finals, and a heat final. There were still two Semi-Finals, but there were now only two rounds in the Semi-Finals. There were four round 1 battles in each Semi-Final, with the winners going to Round 2 of the Semi-Finals, and the two winners going through to the Grand Final.
- Main article: Robot Wars: The Fourth Wars
The format largely remained the same in Series 4. However, there were now only six robots in each Heat. The first round was changed to two three-way melees, with one robot eliminated in each melee, leaving four robots. The rest of the series followed the same format as Series 3.
- Main article: Robot Wars: The Fifth Wars
Series 5 featured only twelve heats, but the amount of robots in each Heat increased back to eight. The Heats followed the same format as Series 3, however, the Semi-Finals featured a new format. There were six robots in each Semi final, with three initial one-on-one battles. For the first time, the three losers went into a three way "Loser's Melee", with only one robot surving to get back into the competition. There were then two more one-on-one battles, with the two winners going through to the Grand Final.
- Main article: Robot Wars: The Sixth Wars
The format was almost entirely unchanged in Series 6 from Series 5. The only change was that Round One now consisted of two four-way melees, with two robots being eliminated in each one. The amount of heats, robots in each show and format of the Semi-Finals stayed the same as Series 5.
- Main article: Robot Wars: The Seventh Wars
As Five took over the show, the format was changed for what proved to be the last time in the show's original run. Whilst the format of the Heats stayed the same as Series 6, there were now 16 heats for the first time since Series 4. The Semi-Finals consequently followed the Series 3-4 format. For the first time, since Robot Wars had moved to a commercial channel, Craig Charles recorded links for the show before and after the advert breaks.
- Main article: Robot Wars: Series 8
The series consisted of six episodes, involving five qualifying heats and a Grand Final, with a sixth finalist being chosen as a wildcard by the judges. There were eight robots per heat, with forty competitors in total.
Four robots fought in each first-round qualifier, of which there are two per heat, allowing two robots to qualify through them, like the two series prior. In the second round, a round robin format was used, where the four robots to qualify out of the first round in each heat all faced each other in a head-to-head battle, even if they had already met in the first round. The winner of each battle was given points, three if the victory is by knockout and two if the battle goes to a judges decision. The two robots with the most points at the end of the round would fight again in the heat final. In the case of a tie, the winner was determined by who won their head-to-head battle. The Grand Final followed a similar format, except that only three robots fight in each first-round qualifier instead of four.
- Main article: Robot Wars: Series 9
The format was unchanged from Series 8, the first time a series had used the same format as a previous one. It maintained the same number of qualifying heats and a Grand Final. The number of competitors per heat and heat structure also remained the same.
- Main article: Robot Wars: Series 10
Series 10 featured the same number of qualifying heats as the previous two series, but the format was changed once again, with the round robin format being dropped. Each heat now featured only six robots for the first time since Series 4, bringing the total number of competing robots to 30; the smallest of any UK Championship.
Each heat was divided up into five rounds. The first round consisted of two three-way melees, but unlike previous series, only one robot qualified through them. The four losing robots were then drawn into the second round, known as the Redemption Knockouts, with the winners joining the melee qualifiers in the third round. The rest of the heat followed the same format used from Series 3 to Series 7, with the exception of a playoff (officially called the 3rd place Wildcard battle) between the two heat semi-final losers that was held between the heat semis and heat final.
The Grand Final once again featured the five heat winners and a Wildcard. Instead of being chosen by the judges, the Wildcard was decided by a ten-robot rumble between the robots that either lost in the heat final or won the 3rd place Wildcard battle. The final followed the same format as the heats, except without a playoff.