He was 25 years old.
"Andrew peacefully passed away in his sleep and in my arms as I told him I loved him this morning. Love you always, Smith," she tweeted.
Smith played from 2010-2013, during which time he was named an Academic All-American. He was on the Bulldogs' roster during the team's championship runs in 2010 and 2011.
The 6-11 big man started 32 of 38 games during the 2010-2011 season and pulled down nine boards during that season's championship game against the University of Connecticut.
But those at Butler say he'll be remembered for more than just his skill on the court.
"What made Andrew special was the way that he genuinely cared for others," Butler President James Danko and Butler Vice President/Director of Athletics Barry Collier said in a statement. "Within his large frame was an even larger heart. He is, was, and always will be a Bulldog."
Boston Celtics coach Brad Stevens -- who coached Smith at Butler -- missed his team's game last Thursday in order to visit his former player.
"I was happy that I got a chance to say goodbye," Stevens said. "He was special. He was tough."
After graduating from Butler, Smith played basketball professionally overseas.
He was diagnosed with a rare form of non-Hodgkin's lymphoma more than two years ago, according to a statement from his family.
He got well enough to go back to work, but then collapsed during the summer of 2014. His heart stopped for about 20 minutes, but paramedics were able to regain a pulse. He was then put into a medically induced coma.
After that scare, Smith got well enough to return to work that September, which his wife called a "miracle."
"Several nurses that had been in the medical world for 30 years made a point to note how they had never seen anything like this," she wrote.
However, in 2015 Smith's wife announced that his cancer had returned.
He received a bone marrow transplant in November, but by December it was clear the procedure had failed.
"We saw the way Andrew fought on the basketball court and we saw the way he fought for his health," Danko and Collier said. "In both cases, we saw the best of Andrew Smith. But that's what we always saw from Andrew. He gave his all, all the time."