Elaine Taylor had claimed her son Liam Tabannor was at home all evening and couldn't have caused the collision on Long Lane.
The incident left a pedestrian in her 50s with life-changing injuries after being hit by his car on November 23, 2018.
Taylor provided the false account after her 27-year-old son was arrested – who went on to admit causing serious injury by dangerous driving.
Liam Tabannor, of Parkfield Road, Oldbury, was jailed for 21 months in November last year at Wolverhampton Crown Court.
Taylor, who lives at the same address, denied perverting the course of justice but was convicted following a trial.
The 57-year-old was sentenced to eight months in jail at Wolverhampton Crown Court on Thursday.
Sergeant Dean Caswell, from the serious collision investigation unit, said: "It's never acceptable to lie to protect somebody who's committed a crime. It doesn't matter if it's a family member, it's wrong and a criminal offence too.
"The woman who was hit by the car suffered life-changing injuries and the driver was rightfully jailed for the collision.
"We were able to pick apart Taylor's story and have now ensured she serves time behind bars too. We won't tolerate deliberate lies to try and avoid justice being served."