The 42-year-old singer, actress and dancer, who rose up through the entertainment world ranks from her humble birthplace of the Bronx, New York, surprisingly jumped from 50th place on last year's list that measures power by entertainment related earnings, media visibility and social media popularity.
Forbes estimated Lopez' earnings in the past 12 months at $52 million (32.67 million pounds), and her top ranking is powered by her lucrative gig as a judge on popular television show, "American Idol," a new clothing line at Kohl's, a top-selling fragrance and millions of Twitter and Facebook followers. She also just announced her first upcoming world tour, joined by Enrique Iglesias.
Winfrey, who has admitted struggling with her OWN TV network after ending "The Oprah Winfrey Show" syndicated TV chat show last year after 25 years, kept her No. 2 slot from last year, earning an estimated $165 million.
Canadian pop star Justin Bieber, 18, also stayed at No. 3 where he debuted last year, earning $55 million, with Forbes reporting he has become a serious investor whose portfolio includes music streaming service Spotify.
Pop star Rihanna landed on the list for the first time with estimated earnings of $53 million due to hits in the past year such as "We Found Love," and "Talk That Talk," while also landing lucrative endorsement deals with the likes of Nivea and Vita Coco, Forbes said.
Dropping four places from last year, Lady Gaga was ranked No. 5, earning $52 million, while new "The X Factor" judge Britney Spears returned to the list after a one-year hiatus landing at No. 6, earning an estimated $58 million helped by a successful tour.
Kim Kardashian was also a notable newcomer at No. 7. She earned $18 million - the lowest amount in the top ten - but attracted ample media attention for her splashy wedding and divorce. Pop singer Katy Perry landed at No. 8.
Rounding off the top ten was Tom Cruise at No. 9 with the comeback success of his "Mission: Impossible - Ghost Protocol" movie that earned nearly $700 million at the global box office, and Steven Spielberg's various ventures in TV and movies earned him an estimated $130 million to place him at No. 10.
British singer Adele entered the list at No. 24 after a record-equalling six Grammy haul and returning to live performing after surgery on her vocal chords.
Among big names to drop off the list was Charlie Sheen after his "Two and a Half Men" exit. His replacement on the show, Ashton Kutcher debuted on the list at No. 51.
The collective earnings power of the top 100 dropped slightly in 2012, with this year's crop earning a collective total of $4.4 billion, down from $4.5 billion in 2011.
The full list can be viewed at www.forbes.com/celebs