Inside centre Michael Hobbs scored a try in the first half, before replacement back Alby Mathewson and captain Luke Braid scored tries after the break to secure the Blues' second victory of a dismal, controversy-tainted season.
The Blues' win, their first since their surprise victory in week three over the Bulls in Pretoria, lifted the home side off the bottom of the standings and consigned the Johannesburg-based Lions to their ninth loss from 10 games.
"Just ecstatic, relieved as well," captain Braid said in a pitchside interview.
"We were a little bit rusty at times but we got the win and that's all that matters... I think the boys will be a lot more relaxed going into the next game against the Crusaders, so we can definitely build on it."
The home side's celebrations were tempered by a leg injury to tighthead prop Charlie Faumuina, who limped off the ground in the third quarter.
Despite committing a rash of penalties in the first half, continuing a frustrating pattern of indiscipline throughout the season, the Blues carried a 10-3 lead into halftime thanks to Hobbs's 17th minute try.
Receiving out wide after a sharp chain of passes, Hobbs ducked inside after feigning a pass to cross the line left of the posts.
The Blues' task was made easier when winger Deon Van Rensburg was sent off nine minutes after the break and Mathewson duly punished the Lions with a try in the 54th minute.
Mathewson took a quick pass out of a scrum deep in Lions territory and scampered 30 metres to plant the ball at the right corner.
The contest meandered wearily through a scoreless, error-strewn phase before Braid was pushed over the line in a rolling maul on the siren to give the Blues a rousing finish ahead of a tough assignment against the Crusaders next week.
After young flyhalf Elton Jantjies slotted a penalty kick in the fourth minute, the hapless Lions were kept scoreless for 76 minutes to be condemned to assuming bottom spot in place of the Blues.