Eucellis grew up in Saraland, Alabama, where her parents worked tirelessly to provide for her and her siblings. In 1994, she graduated from Satsuma High School and pursued higher education, earning a Bachelor of Science degree from the University of South Alabama. Her career began at Searcy Hospital in 1999, and in 2002, she enrolled in law school at Thomas Goode Jones School of Law in Montgomery, Alabama. After four years of commuting, she successfully sat for and passed the Alabama State Bar Exam. In 2007, she became an Assistant District Attorney at the Mobile County District Attorney’s office, where she handled various legal tasks, including trials, plea negotiations, and research. In 2011, she established the Sullivan Law Firm, L.L.C., which has since grown to include representing clients in juvenile cases, custody disputes, divorces, and criminal cases.

Eucellis Sullivan announced on her personal Facebook page on July 3 that she was running in the Republican Primary on March 5, 2024 for the newly created District Judge Place 6 in Mobile County.