The 29-year-old Polish violinist succeeds Bradley Creswick, who held the role with the Royal Northern Sinfonia (RNS) for over 25 years.
Maria Włoszczowska appeared with the RNS on many previous occasions including a recent performance of Vaughn Williams' "The Lark Ascending" on short notice, stepping in for British violinist Jennifer Pike.
Włoszczowska is the 2018 First Prize and Audience Prize winner at the 21st Leipzig International Johann Sebastian Bach Competition and won several prizes at the 15th International Henryk Wieniawski Violin Competition in 2016.
"I am thrilled to be joining the wonderful RNS as Leader. I was immediately taken by the player’s openness, trust, willingness to explore and always go the extra mile — an attitude that creates endless potential and makes them a world-class ensemble," said Włoszczowska.
"I’m delighted to be able to contribute to what is undoubtedly a very exciting future for the group. I’m also keen to get to know the audiences around the region and make this stunning part of the UK my home."
"She is an incredibly talented musician and leader who has already developed a strong relationship with the orchestra over her appearances this season," said Abigail Pogson, Managing Director of the orchestra's venue, Sage Gateshead.