[1] She received a Bachelor of Arts degree, summa cum laude, in 1991 from the University of Virginia.

She received a Juris Doctor in 1997 from Yale Law School.

She began her legal career as a law clerk for Judge Diana Gribbon Motz of the United States Court of Appeals for the Fourth Circuit, from 1997 to 1998.

[2][3] On March 26, 2015, President Barack Obama nominated Xinis to serve as a United States district judge of the United States District Court for the District of Maryland, to the seat vacated by Judge Deborah K. Chasanow, who assumed senior status on October 3, 2014.

Her nomination was reported from the Senate Judiciary Committee on September 17, 2015, by a voice vote.