On 15 July 2016, Smejkal signed with Medveščak Zagreb of the KHL.[4] He left for Sparta Praha on 31 January 2017.[5] On 27 December, Smejkal was loaned to Piráti Chomutov for the remainder of the 2017–18 season.[6]
After the conclusion of Smejkal's contract with Sparta Praha, he moved to Finland and signed one-year contracts with Tappara in May 2020,[7] and then with Lahti Pelicans in July 2021.[8]
As an undrafted free agent, Smejkal signed a one-year, entry-level contract with the Ottawa Senators of the National Hockey League (NHL) on 4 May 2023.[10] The signing came in response to the Senators' stated goal of bolstering its scoring and organizational depth ahead of a 2023–24 season in which they hoped to make the Stanley Cup playoffs for the first time since 2017. Described as a "prototypical power forward", it was hoped that Smejkal's combination of size and skill would help the team achieve that goal.[11] Smejkal was assigned to Ottawa's American Hockey League (AHL) affiliate, the Belleville Senators, to start the 2023–24 season.[9] On 9 December, Smejkal made his NHL debut in a 5–1 win over the Detroit Red Wings.[12][13] He played in two games with Ottawa before being returned to Belleville. He was recalled again, along with Angus Crookshank, on 16 December after injuries to Mathieu Joseph and Rourke Chartier.[14] On 22 December, Smejkal collected his first NHL point, assisting on Jacob Bernard-Docker's goal in a 6–4 loss to the Colorado Avalanche.[15] He played in seven games before being sent back to Belleville on 7 January 2024.[16] He was recalled again on 7 March.[17] However, his stay in the NHL was short, being returned to the AHL after Parker Kelly returned from suspension on 13 March.[18] Smejkal finished his AHL season on 4 April, recording nine goals and 22 points in 46 games with Belleville. He was recalled that day due to an injury to Crookshank[19] and remained with Ottawa until the end of the season. In the final game of the season on 16 April, Smejkal recorded his first NHL goal against Linus Ullmark in 3–1 win over the Boston Bruins.[20]