Early career: Pre-2014 (Ambala youth wing) Saini joined the BJP party unit in
Ambala. Initially, he started working as a computer operator in the BJP's Ambala party office and eventually became the general secretary of Haryana BJP's Kisan Morcha (farmers’ front). He became an active member of BJP's Ambala youth wing, and he was recognized by
Manohar Lal Khattar. He contested the election in
Naraingarh constituency of Ambala district in 2010 but was defeated by Ramkishan Gurjar. While he lost his first election, he was becoming recognized as an OBC face in the BJP's Ambala unit. In 2023, he was appointed the president of the
Haryana unit of the BJP.
Prime Career 2024 onwards (Chief Ministership) Saini, who was the president of
BJP state unit was declared the new Chief Minister of Haryana on 12 March 2024 after incumbent
Manohar Lal Khattar resigned as Chief Minister before
2024 Lok Sabha election. After the resignation of
Manohar Lal Khattar, Saini was elected as the Leader of BJP's Legislative Party and subsequently took oath as the Chief Minister of Haryana. (He also won by-poll from Khattar's former constituency Karnal in May 2024). In October 2024, Saini won the
Haryana Assembly Election from
Ladwa seat (Kurukshetra district) and also became the second time Chief Minister of
Haryana on 17 October 2024. According to political analysts, the elevation of Nayab Singh Saini as Chief Minister in March 2024 helped BJP win the 2024 Haryana elections, as the party was able to consolidate the votes from the OBC community, while and also gaining some Scheduled Caste (SC) voters, through new development schemes.{{cite news |title=Haryana election results 2024: As BJP looks set for win, 5 things the party got right ==Developmental initiatives as CM (2024 onwards)==