Trafford had agreed personal terms with Newcastle last season, but a fee could not be agreed upon between the two clubs. He then went on to set a new EFL record by conceding just 16 goals in the league, which likely caught the attention of Manchester City manager Pep Guardiola.
Guardiola has been looking for a goalkeeper who can match his tactical system, and Trafford is considered one of the best young goalkeepers in Europe. He will join Ederson and Stefan Ortega as City's goalkeepers under Guardiola.
Transfer expert Fabrizio Romano has confirmed the deal, stating that City have agreed to a buy-back clause worth under £40 million. Trafford has chosen to return to City, where he is wanted by Guardiola.
Newcastle United, who have missed out on several transfer targets this summer, including Dean Huijsen and Liam Delap, are also informed of Trafford's decision.