He is a member and the Division Chief of Padang Besar of the United Malays National Organisation (UMNO), a component party of the BN coalition.
On 13 June 2018, Ruzaini was appointed as the Perlis State EXCO Member in charge of Islamic Religious Affairs, Welfare, Disaster Relief, Border Relations and Cooperations by Menteri Besar Azlan.
He won the seat and was elected into the Perlis State Legislative Assembly as the Beseri MLA after defeating candidates of Pakatan Harapan (PH) and Gagasan Sejahtera (GS) by a majority of 416 votes.
In the 2022 Perlis state election, Ruzaini was renominated by BN to defend the Beseri seat.
He lost the seat and was not reelected as the Beseri MLA after losing to Haziq Asyraf Dun of Perikatan Nasional (PN) by a minority of 1,047 votes.