"One of Maxwell's best friends is North," said Simpson, 41, before praising Kanye's 8-year-old daughter. "She is amazing. She is a great kid, and she will be a part of a change in this world."
The fashion designer — who shares Maxwell, 9, with husband Eric Johnson — also revealed that Johnson "just recently" coached North and Maxwell's basketball team.
And not only are North and Maxwell BFFs and teammates, but they are also neighbors! Simpson told Us Weekly that it's "fun" living close to Kardashian and her family. The SKIMS founder shares North as well as son Saint, 6, daughter Chicago, 4, and son Psalm, 2, with ex-husband Kanye West.
"That [proximity] makes it easy," Simpson said of the friendship.
The actress went on to praise how Kardashian and her kids haven't changed despite the many years on reality TV, noting that the family has "remained the same."
"I'm like, 'I don't know how y'all could do this all the time,'" Simpson said. "I could only last three seasons [on 'Newlyweds'], but they're so open and they've always remained the same. … That's really hard to do, and they're powerhouses."
The "Open Book" author — who famously starred in the MTV reality show, "Newlyweds: Nick and Jessica," from 2003 to 2005 with then-husband Nick Lachey — noted that she believes appearing on reality television is "easier" now than it was back then.
"It was one of the first, and so it was [cameras] following me all day long from the moment I woke up to the moment I went to sleep unless I kicked them out, but I always felt bad," Simpson explained. "I don't think that reality shows are set up like that nowadays. I think they have shooting days and that type of thing."
Simpon's marriage to Lachey ended in 2006, and she began dating Johnson in 2010. The two married in 2014. In addition to Maxwell, Simpson and Johnson also share son Ace, 8, and daughter Birdie, 3.