Launchbury was educated at St John’s Sidmouth in East Devon, where he captained the school rugby team, and Christ's Hospital Horsham.

[2][3] After Harlequins failed to offer him a professional contract aged 18, he left the club and joined then National League 2 South side Worthing Raiders for the 2009–10 season.

[5] He played in several A League matches for Wasps and, after a spell training with the Eastern Province Kings in South Africa,[6] did enough to be given a full-time contract from July 2010.

[7] Launchbury was named in Wasps' Academy squad for the 2010–11 season and also joined National League 1 side Rosslyn Park on loan to gain senior experience.

[2][8][9] Having played the first half of the season for the A team and out on loan, Launchbury made his Wasps' debut on 30 January 2011 in the Anglo-Welsh Cup against Harlequins as a replacement, scoring a try in a 38–13 defeat.

[24] Following Wasps' entry into administration, Launchbury signed a short-term deal to join Japanese club Toyota Verblitz from December 2022 to May 2023, for the 2022-23 Japan Rugby League One season.

[25] On 21 November 2022 it was announced that Launchbury would join Harlequins, signing a multi-year deal to return to the club ahead of the 2023–24 season, following his time in Japan.

[28] Despite not being included in the original squad he was elevated to the starting line-up for the following game and earned the Man of the Match award against Ireland as England won the Grand Slam.

[29][30] He was selected for the Junior World Championship in June the same year and started every game as England reached the final, eventually losing 33–22 to New Zealand.

[33][34] The following month he was included in the Saxons squad and in November was called into the England training camp for the Autumn internationals as injury cover for Wasps teammate Tom Palmer.

Launchbury was not selected to be a member of the British an Irish Lions Touring party to New Zealand, which was a controversial call following his success in the Six Nations.