Embodiments herein relate to new and useful systems and methods for tokenization across code trust boundaries. An embodiment includes a method for securing data across execution contexts in a computing device. The method includes determining that first data is to be passed from a first code in a first execution context to a second code in a second execution context. The method further includes, based on determining that the first data is to be passed, tokenizing the first data to generate tokenized first data, wherein tokenizing the first data comprises substituting the first data with second data that is based on the first data to secure the first data from the second code, the second data being the tokenized first data. The method further includes passing the tokenized first data from the first code to the second code.