Melinda Muniz was sentenced to life in prison without the possibility for parole.
Prosecutors said Muniz killed Grace Ford after the toddler's father broke up with her. She then staged a home invasion in her apartment.
The jury deliberated less than an hour before coming back with the guilty verdict.
"I am very happy that justice if finally served for my daughter," said Emily Reeves, Grace's mother, to reporters after the verdict was announced. "It has been a long year for me and my family. It has been a heartbreaking year. But this is going to bring us closure."
Mitch Ford, Grace's father, left the courthouse without comment, but in court told Muniz, his ex-fiancée, "I don't forgive you and I never will."
Defense attorney Robbie McClung says Muniz is worried about what will happen to her 3-month-old son, likely fathered by Mitch Ford, though DNA test results have been sealed.
That child is currently with Muniz's family.
Muniz was expected to take the stand Monday morning as her defense attorneys began presenting a case, but opted not to.
"If you want to get your version of this story out, this is the time to do it," the judge said.
However, she decided against it and her attorneys rested without presenting any evidence or calling any other witnesses.
The judge reminded jurors she had an absolute right to refuse and that cannot be held against her.
The state rested Friday after calling upon several witnesses. A lead investigator testified she believes Muniz suffocated Grace before covering her mouth with duct tape.