Lahren jabbed the rapper on Twitter last week, writing "looks like [Cardi B] is the latest genius political mind to endorse the Democrats."
Lahren added: "Keep it up, guys! #MAGA2020."
In a response, Cardi quoted the tweet and wrote, "Leave me alone I will dog walk you."
"Im sure you would," the commentator replied. "Still doesnt make your political rambling any less moronic."
Cardi B, whose real name is Belcalis Almanzar, hit back against Lahren again, writing she was "blinded with racism."
"Youre so blinded with racism that you dont even realize the decisions the president you root for is destroying the country you claim to love so much," she tweeted. "You are a perfect example on no matter how educated or smart you think you are you still a SHEEP!"
Lahren's first tweet seemed to be replying to a video the rapper had posted last week, in which she criticized federal gridlock over Trump's demands for a $5 billion wall along the US southern border.
"This s--t is crazy," she said in the profanity-laced video . "Like, our country is a hellhole right now, all for a f-----g wall. And we really need to take this serious."
Cardi pointed to the hundreds of thousands of federal government workers who were being forced to work without pay during the shutdown, which had stretched for more than three weeks.
"Now, I dont want to hear yall motherf-----s talking about oh, but Obama shut down the government for 17 days. Yeah, bitch, for health care," she said. "So your grandma could check her blood pressure and you bitches could go check your p---y in the gynecologist with no motherf-----g problem."
The fiery video caused confusion among Democratic lawmakers who supported the points she made in the video, but found it a challenging decision to share the harsh language on social media.
Democratic Sens. Brian Shatz, Chris Murphy, and Minority Leader Chuck Schumer discussed the video in a Twitter thread.
Though the rapper didn't appear to expect such a strong response, asking " why am I trending? " in a tweet later that night.
This isn't the rapper's first appearance in political discourse.
After the February 2018 massacre at Marjory Stoneman Douglas High School in Parkland, Florida, Cardi took to Instagram to criticize Trump's response, which included a proposal for arming teachers, writing of the president, " this man really out his mind. "
In April 2018, Sen. Bernie Sanders endorsed Cardi's praise, in a GQ profile, for former President Franklin Delano Roosevelt's creation of Social Security as part of a push for reforms to the program.