Rosenthal became a law student and moved from Warsaw to Paris, during the Polish revolution in 1864 after the failure of the January Uprising. He settled in Paris as where he became a chess professional and writer.
In 1864, he lost a match to Ignatz von Kolisch (+1 –7 =0) in Paris, won the Café de la Régence championship in 1865, 1866, and 1867 and became the strongest French chess player. In 1867, he took 9th in the Paris tournament, lost a match to Gustav Neumann (+0 –5 =6), in 1869 he lost two matches to Neumann (+1 –3 =1) and (+2 –4 =1) and in 1870, he tied for 8–9th in Baden-Baden.
Because of the Franco Prussian War of 1870–71, Rosenthal went to London. In 1870/71, he won a match against John Wisker (+3 –2 =4). In 1873, Rosenthal took 4th in Vienna, tied for 7-8th in Paris. In 1880, he won in Paris the first unofficial French Chess Championship and in 1880, he lost a match against Zukertort (+1 –7 =11) in London. In 1883, he took 8th in London and in 1887 he tied for 5–7th in Frankfurt am Main (5th DSB–Congress, Hauptturnier, elimination tournament). His results were affected by his journalistic activities and bad health.
From 1885 to 1902, he edited a chess column for the Le Monde Illustré and wrote for La Strategie, La Vie Moderne, and other French newspapers.
Rosenthal once engaged in a court battle with one of his students, Prince Balaschoff, for breaking his lesson contract. The lawsuit was brought before the first Chamber of the Civil Tribunal of Paris. Rosenthal had been a resident of Paris and had been engaged for ten yearsby Prince Balaschoff as his professor of chess at £ 25 per month, to be increased to £40 per month whenever the Professor traveled with his pupil. They were on the best of terms for many years and were collaborating on a chess book when Rosenthal was unceremoniously dismissal. He sued for £ 750 back salary according to their written agreement, £50 for a final journey to Stuttgart, and £1,250 for his unjustifiable dismissal and loss of profits on the projected book. The Civil Tribunal allowed the first claim, but rejected the others.
Rosenthal was a remarkable figure. Although he never attained the highest level he distinguished himself by promoting chess in France, his adopted country. After he arrived in France as a political refugee and began a somewhat precarious existence in Paris as a chessplayer at the Cafe de la Regence. His matches with Neumann showed that he was a strong and resourceful player and encouraged him to challenge Zukertort. Though he took a beating in the match, at London 1883 he defeated Steinitz twice.
After this he confined himself to correspondence chess and teaching where he was popular with the aristocratic amateurs in Paris. It's reported that he amassed a larger fortune from chess than any of the other professionals of the day. According to the magazine Checkmate, Rosenthal wrote a book on the Paris tournament of 1900 that was of very poor quality.
Rosenthal's best tournament performance was his forth place finish at Vienna, 1873 where he defeated Bird and Paulsen. The following game which was played in the last round against Blackburne features the Kieseritsky Gambit against which Rosenthal employed an ancient and forgotten defense which won the game. In doing so Rosenthal proved Lasker's point that even the worst variation is good enough to be played...once.