2015–16

On 7 July 2015, Haraslín joined Lechia Gdańsk on a three-year deal, although an apparent interest was reported from numerous clubs, yet some only requested Haraslín on a loan.^[2]

Haraslín debuted for Lechia Gdańsk on 16 August 2015 a wild 3–3 tie against Wisła Kraków.^{[citation needed]} Although Haraslín was only fielded in the second half, coming on as a substitute for Bruno Nazário, he scored just after six minutes on the pitch, setting the score to 2–2. The following week, Haraslín scored 2 in a 3–1 win over Górnik Łęczna. In late October Haraslín suffered an injury that kept him out of action until early December. After he returned, he played in almost all of the games, although mostly as a substitute. He completed the season with 3 goals in 20 games.

2016–17

At the beginning of the 2017–18 season it was announced the Haraslín had extended his contract with Lechia. The new deal was a two-year one, set to expire in June 2020.^[3]

2018–19

During the 2018–19 Ekstraklasa, in addition to 4 league goals, Haraslín scored his first Polish Cup goal in a second round 3–1 victory over Resovia Rzeszów, after a pass from Jarosław Kubicki. Unlike in the league, Lechia managed to triumph in this competition, beating Jagiellonia Białystok 1–0 in the final. Haraslín played the entire match at Warsaw's Stadion Narodowy. While this was Haraslín's first trophy in Poland, his fellow Slovak goalkeeper Dušan Kuciak won his fifth cup trophy this season.^[4] The victory made Lechia eligible for a 2nd qualifying round of the Europa League, with Gdańsk hosting the final of that edition.

At the end of 2018, Haraslín was named Lechia's fan-favourite.^[5] In January 2019, it was reported that Galatasaray had notable interest in Haraslín's services,^[6] yet even Inter Milan, A.S. Roma, Atalanta Bergamo and Dijon were reportedly interested.^[7]

However, the transfer did not advance as Lechia was in a battle for the championship. In an article published on 17 May 2019, Michał Gałęzewski stated that Lechia appears to lack a replacement for Haraslín and while a move was expectable and comprehensible, he noted it may not happen.^[8]

Even due to an injury and poor performances in late May, Rafał Sumowski from Troj Miato also stated that it seemed to lack future potential employers.^[9] Haraslín started in Polish Cup final game against Jagiellonia Białystok playing most of the game as Lechia won the cup.^[10] Haraslín also played an important role during the 2018–19 season as Lechia finished third in the season, Lechia's joint highest finish in the league.^[11]

2019–20

The 2019–20 season saw Lechia qualify for the 2019–20 UEFA Europa League and saw them play in the Polish SuperCup. Haraslín scored twice in the SuperCup final as Lechia beat Piast Gliwice 3–1.^[12][13] In the Europa League Lechia were drawn against Brøndby IF.^[14] Haraslín played in both games as Lechia lost the tie 5–3 on aggregate.^[15][16] Haraslín made his 100th appearance for Lechia in July 2019 against Wisła Kraków.^[17][18] In total Haraslín made 121 appearances for Lechia with 16 goals in all competitions.

Debut

On 28 May 2019, Haraslín was called up for a June home friendly match against Jordan and UEFA Euro 2020 qualifying fixture against Azerbaijan.^[24] He debuted against the former opponent at the Štadión Antona Malatinského in Trnava on 7 June 2019.^[25] Haraslín utilised his speed against the tiring Jordanian defenders, who had just recently completed the fasting of Ramadan.^[26] After the match, Haraslín was reported to receive the unofficial title of the man of the match in his debut.^[27]

UEFA Euro 2020

In December 2022, Haraslín was called up for senior national team prospective players' training camp at NTC Senec as one of the experienced leading players in the squad due to his previous absence last autumn.^[28] With praise from Calzona for his recent form, Haraslín returned ahead of two home qualifiers against Luxembourg and Bosnia and Herzegovina.^[29]