The ITU World Triathlon Series is the International Triathlon Union's annual series of triathlon events used to crown an annual world champion. There are multiple rounds of competitions culminating in a Grand Final race. Athletes compete head-to-head for points in these races that will determine the overall ITU world champion. The elite championship races are held over two distances the standard and the sprint distance.
As of 2018 a mixed relay series is to be run in tandem, where national teams compete in mixed team relays for prize money and Olympic qualifying points. One of these races will be the ITU Triathlon Mixed Relay World Championships.
The world champion was formerly crowned in the ITU Triathlon World Championship, a single championship race that was held annually from 1989, the same year as the formation of the International Triathlon Union (ITU), to 2008. Beginning with the 2009 racing season the ITU Triathlon World Championship was changed to a series of events culminating with a grand final race. From 2009 to 2011 the events were known as the World Championship Series (WCS) before being relabeled World Triathlon Series (WTS) in 2012. In 2011 the sprint distance world championship was incorporated into the series giving the same points and prize money as any other event, from this point on sprint distance events would make up a part of the series. In 2013, the series offered a total of $2.25 million in prize money to elite athletes, making it the richest series in triathlon.With the growing popularity of the ITU Triathlon Mixed Relay World Championships and the disciplines addition to the Olympic program  it was decided that at three of the events on the 2018 calendar a mixed relay event would be held alongside the men's and women's competition these three events would grant points towards Olympic qualification and constitute the new ITU mixed relay series.
Currently there are three different distance disciplines:
- Standard- A 1500m swim followed by a 40 km cycle followed by a 10 km run.
- Sprint- A 750m swim followed by a 20 km cycle followed by a 5 km run.
- Mixed Team Relay- A 4 x ( 300m swim followed by a 7.5 km cycle followed by a 1.5 km run) where each athlete completes the swim bike run before tagging the next athlete, with the order of the athletes always being female, male, female, male.
In all instances the swim will be a mass start in open-water and the cycling will be draft-legal. There is an allowed leniency of 10% on each segment of courses route for the standard and sprint distances, with more discretion being allowed for the mixed relay. The standard distance was also known as the Olympic distance as it was the only distance competed for in the Olympics, however the ITU has tried to enforce the use of the name standard distance saving the name Olympic on for official Olympic events.
The athlete won his first title as World Champion under the old world championship system.
The athlete won the title of World Champion under the old world championship system.
- World Triathlon Series locations
GF = Grand Final
- World Triathlon Series Grand Final locations
||Gold Coast, Australia|
||Auckland, New Zealand|
||London, Great Britain|
||Chicago, United States|
||Gold Coast, Australia|
ITU Triathlon World Championship
The world champion was formerly crowned in the ITU Triathlon World Championship, a single championship race that was held annually from 1989, the same year as the formation of the International Triathlon Union (ITU), to 2008.
||Orlando, United States|
||Manchester, United Kingdom|
||Wellington, New Zealand|
||Cleveland, United States|
||Queenstown, New Zealand|
||30 August–2 September