2023–24 LEN Challenger Cup

The 2023–24 LEN Challenger Cup was the 2nd edition of a water polo competition organised by the Ligue Européenne de Natation (LEN). It acts as the third tier, below the LEN Champions League and the LEN Euro Cup. The reigning champions are GS Apollon Smyrnis, but they won't defend their title due to their involvement in this season's Champions League and Euro Cup.

Galatasaray won the competition, beating Slovenian side, Triglav Kranj, in the final. They become the first men's water polo team from Turkey to win a European title.

Format
This is the first season under the new changes made by LEN. 19 teams are grouped into 4 pools, three with five clubs, and one with four clubs. The pools are held by one of the clubs. The top 2 from every pool advances to the quarter-finals, followed by semi-finals and finals.

Rankings
Only teams below the top 12 can enter the competition.

Teams
The team were announced on 8 September 2023. Starting this season, no countries ranked in the top 12 of the LEN men's club rankings can take part in this tournament.

Draw
The draw was on 11 September 2023. H indicates which club is hosting the groups. Teams in bold advanced to the quarter-finals. The seeding was decided by as follows:
 * The new LEN club rankings.
 * LEN country club rankings.
 * LEN men's national team rankings.

Group A
Held in Porto, Portugal

Group B
Held in Mouscron, Belgium

Group C
Held in Istanbul, Turkey

Group D
Held in Valletta, Malta

Draw
The draw took place on 24 October in Barcelona. The seeded and unseeded clubs consist of the teams that finished first and second in the previous round respectively. The only restriction was that clubs from the same group in the previous round could not be drawn against each other.

Bracket


Quarter-finals
 EVK Zaibas won 35–14 on aggregate.

 Galatasaray won 25–18 on aggregate.

 Triglav Kranj won 29–21 on aggregate.

 SC Kreuzlingen won 27–26 on aggregate.

Semi-finals
Galatasaray won 21–17 on aggregate

 Triglav Kranj won 21–20 on aggregate

Final
Galatasaray won 33–19 on aggregate