Juti starts her role on 16 May. She will join Heineken's executive team, reporting to CEO and chair Jean-François van Boxmeer.
She has previously held a number of senior commercial, comms and marketing roles, including 14 years in the US, Mexico and Finland with Nokia, before joining Rovio in October 2013, and staying with the firm until the end of 2015.
O'Neill, who has worked for Heineken in the Netherlands for 12 years, will return to the UK and work at the global brewer in a transition period until the end of June.
Before joining Heineken, O’Neill was global brand and market communication director at Diageo, and before that was communication and corporate affairs director at Diageo-owned Guinness.
Van Boxmeer said: "Sean has been an important member of our executive team for 12 years and has made a significant contribution to our business.
"Blanca has an outstanding track record in leading high performing teams across businesses and functions. Blanca's considerable experience as a member of senior leadership teams coupled with her understanding of company purpose, reputation and her brand and digital communication skills will be valuable assets in meeting the challenges we face in the coming years."