The first daughter was there as an invited guest as Justice Anthony Kennedy, whom she met at the inaugural lunch at the Capitol last month just after her father's swearing-in ceremony.
Supreme Court justices often host guests for arguments, and there is a gallery in the courtroom where visitors are able to observe the judicial branch in action. Trump was in a VIP section where special friends and invited guests sit, opposite from the press gallery.
Trump listened to a technical case examining the question: "Do Arbitration Agreements between Nursing Homes and Patients Violate Public Policy or are they enforceable under the Federal Arbitration Act."
Her daughter, Arabella Kushner, accompanied her mother. The 5-year-old was also at her mother's side at a Lunar New Year party at the Chinese embassy earlier this month.
The two left just before noon, stopping at the top of the steps of the Supreme Court building to smile for cameras. Trump declined questions as Arabella skipped to a waiting SUV.
Trump posted an Instagram of her and her daughter on the steps shortly thereafter, writing, "Arabella and I visited the Supreme Court this morning and attended a hearing. I'm grateful for the opportunity to teach her about the judicial system in our country firsthand. #SCOTUS #SupremeCourt #ImportantLessons #MotherDaughter"
Trump, who was a key adviser to her father's campaign but does not have a formal White House title, has taken an active interest in her father's administration. Last week, she attended his event at a Charleston, South Carolina, Boeing factory, and helped host a women's business initiative alongside the President and Canadian Prime Minister Justin Trudeau.
Trump also spoke out against anti-Semitic behavior Monday evening, tweeting: "America is a nation built on the principle of religious tolerance. We must protect our houses of worship & religious centers. #JCC."
President Donald Trump later followed his daughter's lead, condemning anti-Semitism and bomb threats against Jewish Community Centers at a Tuesday visit to the National Museum of African American History and Culture.
The White House confirmed the visit but did not provide any additional details.