Ma Rong was a representative of the old-character school (guwen jingxue 古文經學). He occupied the office of an editor (jiaoshulang 校書郎) and was promoted to manager of the scribes (dian jiaomishu 典校秘書) of the library in the Eastern Hall 東觀. Because he had a rift with the powerful family of Empress Dowager Deng 鄧太后 he had to leave his post. Only after the death of the Empress Dowager he was appointed a post as gentleman of the interior (langzhong 郎中) and later governor (taishou 太守) of the commandery of Nanjun 南郡.
Later on he was allowed to return to the Eastern Hall as a court gentleman for consultation (yilang 議郎), yet he soon retired and became a privat teacher. Ma Rong was famous for his less strict observation of the rules of etiquette and discussed with his disciples while in the background, women entertained themselves. He is therefore often seen as a forerunner of the trend of "pure discussion" (qingtan 清談) or conversational speech that became à la mode during the Jin period 晉 (265-420).
Ma Rong was an expert in all Confucian Classics and was often consulted for advice. He wrote commentaries to virtually all of the Classics and was especially good at resuming the teachings of earlier commentators. To Jia Kui's 賈逵 commentary to the Zuozhuan 左傳 he said that it was excellent but too narrow, while Zheng Zhong's 鄭眾 commentary was very comprehensive, but superficial. He therefore joined their interpretations in his own book Chunqiu sanzhuan yitong shuo 春秋三傳異同說, which is the first large commentary to the Chunqiu 春秋 "Spring and Autumn Annals" and its three old commentaries (Zuozhuan, Gongyangzhuan 公羊傳 and Guliangzhuan 穀梁傳).
He also wrote a commentary on Master Fei's version of the Yijing 易經 "Book of Changes" with the help of quotations of Confucius' disciple Zixia 子夏 and other versions of the Yijing (Meng Xi 孟喜, Liangqiu He 梁丘賀 and Jing Fang 京房). He commented the Shangshu 尚書 "Book of Documents" on the basis of the commentaries of Zheng Zhong and of Jia Kui, and the Shijing 詩經 "Book of Songs", considering both the version of Mao Heng 毛亨 and that of Han Ying 韓嬰.
Ma Rong furthermore wrote commentaries on the three ritual classics, the Xiaojing 孝經 "Classic of Filial Piety" and the Lunyu 論語 "Confucian Analects", as well as to the Daoist texts Laozi 老子 and Huainanzi 淮南子, the Lienüzhuan 列女傳 and the southern elegy Lisao 離騷.
His writings also include many rhapsodies, memorials, treatises and eulogies. Unfortunately all his commentaries on the Classics are lost. Fragments have been collected by the Qing-period 清 (1644-1911) scholars Ma Guohan 馬國翰 (Yuhan shanfang jiyi shu 玉函山房輯佚書) and Huang Shi 黃奭 (Hanxuetang congshu 漢學堂叢書).