The Runaways and X-Men: Pixie Strikes Back artist will share pencilling duties with current artist David Lafuente.
"David is an amazing talent and just wasn't able to put together a monthly schedule for himself. He can only do so many books a year," series writer Brian Michael Bendis told CBR.
"The plan is to up the number of Ultimate Comics Spider-Man issues we put out in a year. Not to what we were doing in the days I was working with Mark Bagley, but maybe between 14-16 issues a year. So instead of losing him totally, David and Sara will co-draw the book together.
"Both of them will be working at the same time. They'll switch back and forth between story arcs."
Pichelli will make her debut on the title in October's Ultimate Comics Spider-Man #15.