The Supreme Court ruled that Sidhu "intentionally caused hurt" to Gurnam Singh, who was 65, resulting in his death in the incident in 1988.
The former MP was acquitted of the more serious charge of manslaughter in 2018 - that still stands.
But the jail sentence is a serious setback for his political career.
Sidhu was first accused of manslaughter in 1988 when a 65-year-old man died hours after an argument with him in Patiala.
He was India's opening batsman at the time and a rising star in his fledging international cricket career.