Trans-Sahara Counterterrorism Partnership Program Act of 2021 This bill provides statutory authority for the Trans-Sahara Counterterrorism Partnership Program, an interagency program launched in 2005 to partner with countries in the Sahel and Maghreb regions of Africa to counter terrorism and violent extremism. The Department of State, in consultation with the Department of Defense and the U.S. Agency for International Development, shall establish the partnership program, which must coordinate all U.S. programs in North and West Africa related to various counterterrorism activities, such as building foreign-military capacity, enhancing border security, promoting youth employment, and supporting independent media to counter terrorist propaganda. The State Department must submit comprehensive, five-year strategies that include specified activities for the Sahel and Maghreb regions and for program counterterrorism efforts. Further, program activities must, among other things (1) be carried out in countries where there is an adequate level of partner country committment, and (2) have clearly defined outcomes and specific plans with indicators to regularly monitor and evaluate outcomes and impact. Such activities must also take into account the counterterrorism and development strategies of partner countries and align with such strategies to the extent possible. The State Department shall notify Congress before obligating funds for such programs, and must submit annual reports about program activities.