Backed by her hit single "Come & Get It," 21-year-old Gomez's fourth studio album, "Stars Dance," sold 97,000 in the past week, according to figures compiled by Nielsen SoundScan.
Jay-Z, whose album "Magna Carta Holy Grail" topped the chart for two weeks, fell to No. 2, selling 77,000 copies.
The soundtrack to "Teen Beach Movie," a Disney Channel film, rose to No. 3 from No. 8 with 57,000 in sales during the week.
Walt Disney Co's Disney Music Group labels Walt Disney Records and Hollywood Records released "Teen Beach Movie" and Gomez's "Stars Dance," respectively.
Compilation album "Kidz Bop 24" of children singing pop hits fell one spot to No. 4, selling 39,000 copies, and Latin pop singer Marc Anthony's Spanish-language album "3.0" debuted at No. 5, selling slightly fewer than 39,000 copies.
Anthony's album is the highest-selling opening week for a Spanish-language album since 2011, Billboard said.
Other debut albums to break into the top 10 are "Tracing Back Roots" by rock group We Came as Romans at No. 8 and "Rich Gang," a compilation from the rap labels Young Money Entertainment and Cash Money Records, at No. 9.
Overall album sales for the week ending July 28 totaled $4.68 million units according to Billboard, down 4 percent from the same week in 2012.