The SPIRIT 2024 and CONSORT 2024 reporting guidelines were developed through a collaborative process involving experts from various fields. The development aimed to harmonize the two guidelines, align them with current evidence and best practices, and improve usability for users. A scoping review identified suggestions for revisions and additions to the existing SPIRIT 2013 and CONSORT 2010 guidelines. These suggestions, along with input from stakeholders, were used to generate a list of potential changes. An international Delphi survey was conducted to reach consensus on these changes, with three rounds of anonymous feedback from participants. The results of the Delphi survey were discussed in an expert consensus meeting, where participants agreed on implementing 11 of the proposed changes and supported further changes that had not reached consensus. The final checklists were revised based on feedback from the Delphi survey and the consensus meeting. SPIRIT 2024 contains 34 items, and CONSORT 2024 contains 30 items. The updated guidelines aim to provide more consistent guidance for reporting randomized controlled trial protocols and results, respectively. The development process included extensive stakeholder input, and the checklists were revised to simplify the user experience and improve clarity. The SPIRIT and CONSORT checklists were harmonized where appropriate, and content from key extensions was incorporated to facilitate more complete reporting. The final checklists represent consensus on the minimum content that should be reported. The development of the SPIRIT 2024 and CONSORT 2024 Statements was informed by current empirical evidence and extensive input from stakeholders. The updated guidelines aim to improve the completeness and consistency of reporting in randomized controlled trials.The SPIRIT 2024 and CONSORT 2024 reporting guidelines were developed through a collaborative process involving experts from various fields. The development aimed to harmonize the two guidelines, align them with current evidence and best practices, and improve usability for users. A scoping review identified suggestions for revisions and additions to the existing SPIRIT 2013 and CONSORT 2010 guidelines. These suggestions, along with input from stakeholders, were used to generate a list of potential changes. An international Delphi survey was conducted to reach consensus on these changes, with three rounds of anonymous feedback from participants. The results of the Delphi survey were discussed in an expert consensus meeting, where participants agreed on implementing 11 of the proposed changes and supported further changes that had not reached consensus. The final checklists were revised based on feedback from the Delphi survey and the consensus meeting. SPIRIT 2024 contains 34 items, and CONSORT 2024 contains 30 items. The updated guidelines aim to provide more consistent guidance for reporting randomized controlled trial protocols and results, respectively. The development process included extensive stakeholder input, and the checklists were revised to simplify the user experience and improve clarity. The SPIRIT and CONSORT checklists were harmonized where appropriate, and content from key extensions was incorporated to facilitate more complete reporting. The final checklists represent consensus on the minimum content that should be reported. The development of the SPIRIT 2024 and CONSORT 2024 Statements was informed by current empirical evidence and extensive input from stakeholders. The updated guidelines aim to improve the completeness and consistency of reporting in randomized controlled trials.