London Lions are a British professional basketball team based in Stratford, East London, England, and compete in the Super League Basketball (SLB).

The team was originally founded in 1977 as the Hemel Hempstead Lakers. Following an ownership take over by Vince Macaulay in 1993, the club subsequently relocated to Watford, and then Milton Keynes, where they were known as Milton Keynes Lions. It was in Milton Keynes that the team won its first silverware in 2008, the BBL Cup. The Lions relocated to London in 2012 and play its home games at the Copper Box Arena in the Queen Elizabeth Olympic Park, as well as occasional EuroCup matches at Wembley Arena.

The Lions were purchased by 777 Partners in 2020, ending Macaulay's 27-year tenure. After the threat of bankruptcy following their owners' collapse amid claims of financial fraud at the end of the 2023–24 season, the club was rescued for the 2024–25 season under the ownership of Tesonet, minority shareholders of BC Žalgiris.

The club initially started out based in the town of Hemel Hempstead, 24 miles northwest of London, and were known as the Hemel Hempstead Lakers. The team was named after one of the National Basketball Association's (NBA) most famous teams, Los Angeles Lakers, and even adopted their colours of purple and gold. In 1977, the Lakers entered the National Basketball League's Division 2, and enjoyed a rather successful first season, finishing fifth (from 11 teams) with a 10–10 record. Their second season would be even more successful, with the Lakers finishing second in Division 2 (15–3) and winning promotion to the top-level league Division 1.

With entry into the country's top league ensured, the club received a major sponsorship deal from beverage brand Ovaltine, and as part of the deal were known as Ovaltine Hemel Hempstead. The franchise became a formidable force in Division 1, regularly finishing at the top-end of the table and making many appearances in the Play-off semi-finals at Wembley Arena, finishing third in 1981. Following the end of the Ovaltine sponsorship and a one-year deal with retailers Poundstretcher, the franchise was rebranded as the Hemel Royals in 1985. Meanwhile, on court, the team failed to reproduce the performances of the past few seasons and often settled for mid-table positions. This was a golden period in British Basketball and Hemel regularly brought top American talent from the States. Dick Miller is the greatest defensive player in the franchise's history and probably the game as a whole in the UK. The enigmatic Harvey Knuckles is considered one of the greatest players ever to play in Britain. Steve Hale was a fourth round draft pick, Sam Smith scored big points from all round the court and Daryl Thomas was a prolific scorer.

For the 1989–1990 season the franchise opted to leave the top-tier (now known as the Carlsberg League due to sponsorship from the Carlsberg Group) and return to the second-tier league, which had been renamed as NBL Division 1. After only one season, and a fourth-place finish (14–8), the Royals returned to Carlsberg League. The team finished bottom of the league in the 1992–1993 season with a 4–29 record, and were subsequently relegated back to Division 1, however they were later reinstated and returned to the rebranded BBL for the following season. A dismal spell ensued and over the next decade the team wouldn't finish outside of the bottom three, but with the removal of the promotion/relegation system between the BBL and Division 1, this had little consequence.

The lack of fortune and an aging venue prompted the franchise to look at relocating and the team found a suitable, yet temporary solution in the neighbouring town of Watford. In preparation for the move, the franchise was rebranded as Hemel & Watford Royals in 1996 and they made the move from the Dacorum Centre to Watford Leisure Centre in 1997. The move had little effect on the team's playing performance and they finished 13th out of 13 in the 1997–1998 season (3–33). Royals' stay in Watford lasted just one season and, in 1998, with the promise of a future purpose-built arena being offered in the town of Milton Keynes, the team packed up, moved and renamed themselves as the Milton Keynes Lions.

Lions' on-court performances were an instant improvement and the franchise began a slow but noticeable turnaround, reaching the semi-finals of the National Cup and also the end-of-season Play-offs for the first time in eight seasons in 2000. After a hugely successful run, the franchise reached its first major final in 2002 with an appearance at the SkyDome Arena in the BBL Trophy. The Lions fought valiantly but eventually lost to the all-conquering Chester Jets, losing 90–89 in a close contest. From then on, the Lions remained a competitive force in the league, often qualifying for the post-season Play-offs (though having little impact on the outcome), and an appearance in the BBL Cup Semi-final in 2005 was considered to be a major landmark.