Women and Minorities in STEM Booster Act of 2021 This bill requires the National Science Foundation to award competitive grants to enable eligible entities to carry out the activities specified below in order to increase the participation of women and underrepresented minorities in the fields of science, technology, engineering, and mathematics (STEM). An eligible entity that receives a grant shall use grant funds to carry out one or more of the following activities designed to increase the participation of women or minorities underrepresented in science and engineering, or both: online workshops, mentoring programs that partner STEM professionals with students, internships for undergraduate and graduate students in STEM fields, outreach programs providing elementary and secondary school students with opportunities to increase their exposure to STEM fields, and programs to increase the recruitment and retention of underrepresented faculty.