"Given the history of the ward, the political history of the ward, I think Natashia represents a clear break from the past and a new beginning," Mayor Emanuel said.
He added that the appointment is "the writing of a new chapter for the city".
Jackson resigned last month.
"The power of a community depends on the power of our partnerships," Holmes said. She said she plans to hit the ground running by meeting with community groups and law enforcement officials.
Holmes, who is new to politics, holds a law degree and will take the bar exam in July. Previously, she worked as a senior policy planner with the State Department of Transportation.
She once ran for school board, but hasn't run for any other office.
"She had no kids in the school, but knew how important a school was to a neighborhood," Mayor Emanuel said.
About becoming alderman, Holmes said, "I thought it was a longshot, but turned into an opportunity."
She is Mayor Emanuel's first aldermanic appointment- a recommendation made by a small committee of community leaders and his staff, who sifted through four dozen applicants.
Emanuel said the selection process used for Holmes will be the template for future aldermanic vacancies.
Holmes begins with less name recognition than her predecessor, but, according to Emanuel, she holds the energy and intellectual vigor that is needed for the position.
When asked if she had any plans to consult with Jackson on a transition, Holmes says "it's time to move forward."
"It's a new days for the ward so we're starting over," said Holmes.
She will be sworn-in on Wednesday.