Jakub Martinec (born 13 March 1998) is a Czech professional footballer who plays as a defender for Czech First League club Sparta Prague. He represented Czech Republic at youth level.
Martinec captained Czech National Football League club Hradec Králové in his final season there.
On 11 August 2020, he signed a 3-year contract with Czech First League side Jablonec.
Martinec said in an interview, he didn't celebrated his goal out of respect, when he scored a goal against his former club Hradec Králové on 11 September 2022.
On 5 September 2025, Martinec signed a multi-year contract with Czech First League club Sparta Prague.