Anderson was born in Baltimore, Maryland, in 1981,^[9] the second youngest of five sons.^[3] He attended Princeton University, where he received his B.A. degree, and then the University of Notre Dame, where he earned a Ph.D.^[10]

In November 2003, Anderson wrote an article for the Daily Princetonian, the student newspaper at Princeton University, comparing what he labeled homosexual "characteristics" and homosexual "acts" to "alcoholism" and "the crimes of a pedophiliac priest" in arguing for his religious beliefs about homosexuality.^[11][4][5]

In February 2007, Anderson wrote an article for First Things, a conservative journal, about his friend in which he speculated about his "problem" of same-sex attraction, said that his friend "suffers" same-sex attraction, mused about a "cure" for homosexuality, and claimed homosexuality as amidst "disorders".^[12][4][5]

In 2012, Anderson wrote an article in which he promoted an article about advocates for a cure for homosexuality who fought against laws that ban the practice of conversion therapy on children and quoted his previous article in justification.^[13][4][5]

In 2012, Anderson co-authored the book What Is Marriage? Man and Woman: A Defense with Sherif Girgis and his mentor Robert P. George, published by Encounter Books.^[3][14] In it, they argued that the purpose of marriage is reproduction and thus same-sex marriage should not be possible. Justice Samuel Alito referenced the book in his dissenting opinion in United States v. Windsor.^[3][15]

In 2014, Anderson wrote a dissertation titled Neither Liberal Nor Libertarian: A Natural Law Approach to Social Justice and Economic Rights, advised by University of Notre Dame professor Michael Zuckert.^[10][2]

In 2017, Anderson co-wrote the book Debating Religious Liberty and Discrimination with Girgis and John Corvino. The book received positive reviews for its constructive, back-and-forth discussion on religious freedom and anti-discrimination law.^[16][17]

In 2018, Anderson released his book When Harry Became Sally: Responding to the Transgender Moment.^[18][19][20] The book, critical of what Anderson calls "transgenderism" and heavily influenced by the works of Paul R. McHugh, came under scrutiny after it topped the Amazon bestsellers list in the Gay & Lesbian Civil Rights History category.^[21]

In 2019, Anderson wrote in opposition to a state law in Massachusetts that bans the practice of conversion therapy on children.^{[22][23][4][5]}

In 2020, Anderson co-wrote an article with his mentor Robert P. George in which they described homosexual "inclinations" as "disordered" in criticizing Pope Francis for his support for the legal recognition of same-sex couples.^[24][4][5]

On February 21, 2021, Anderson's book, When Harry Became Sally: Responding to the Transgender Moment, was removed from Amazon.^[25]

In February 2021, Anderson wrote an article in opposition to the Equality Act, which is a bill in the United States Congress that would ban discrimination based on sex, sexual orientation, and gender identity in federal law.^[26]

On March 11, 2021, Amazon explained its decision in a letter addressed to Republican Senators Marco Rubio, Mike Lee, Mike Braun, and Josh Hawley.^[27] Anderson denied that his book described transgender people as "mentally ill."^[28]

Anderson is a Catholic.^[29]

• Ryan T. Anderson on Twitter