Jinnah left London for India in 1896. He decided to go to Bombay after a brief stay in Karachi. He opted for Bombay because it offered scope for the exercise of his legal faculties and ground for his political ambitions. Bombay had the brightest constellation of India's lawyer-politicians, at that time. Ranade, Badruddin, Tyabji, Gandhi, Tilak, Gokhale, Cowasji, Dadabhoy Naoroji, Bholabhai Desai, Wacha, Nariman and many more renowned men were based in Bombay.
He was enrolled as a barrister in Bombays' high court on August 24, 1896. He took up lodgings in Room No.110 of Apollo Hotel. Father's business had suffered serious losses by then, and he could hardly get any brief for a year or so but he never stopped helping the poor and needy, even in his precarious financial position. In a letter to the Times of India, Bombay, the June 10, 1910 issue, he appealed to the well-off section of the Muslim Community in Bombay to aid a Muslim orphanage in the city. He donated a handsome amount to the orphanage at a time when his practice was not even flourishing. By 1900, he was introduced to Bombay's acting advocate-general, John Molesworth McPherson, and was invited to work with him in his office. But soon he succeeded in crossing all the hurdles to become a leading lawyer of India. He won many famous cases through powerful advocacy and legal logic.
In politics, he admired Dadabhai Naoroji and another brilliant Parsi leader Sir Pherozeshah Mehta. It was Pherozeshah Mehta, who entrusted him to defend him in the famous Caucus Case. Jinnah hit the headlines in this case; it was remarkable how a 62-year-old statesman of the Congress and an eminent lawyer had entrusted his defence to a young Muslim barrister.
Jinnah's career as a lawyer is full of marvelous legal victories. Either it was the Sapru-Jinnah encounter in Bhopal high court or the famous Bawla murder trial of 1925; a legal case against the great Hindu leader Bal Ganghadhar Tilak or his last case in 1945 where he defended Bishen Lal at Agra; Jinnah always proved to be the most enviably popular counsel.
Sir Stafford Cripps called Jinnah the most accomplished lawyer — outstanding amongst Indian lawyers and a fine constitutionalist. As a fellow barrister of Bombay High Court put it, "he was what God made him, a great leader. He had sixth sense: he could see around corners. That is where his talents lay…he was a very clear thinker…But he drove his points home — points chosen with exquisite selection –show delivery, word by word."
Joachim Alva said "he cast a spell on the courtroom…head erect, unruffled by the worst circumstances. He has been our boldest advocate." Jinnah's most famous legal apprentice M.C. Chagla, the first Indian Muslim to be appointed chief justice of the Bombay High Court said, "What impressed me the most was the lucidity of his thought and expression. There were no obscure spots or ambiguities about what Jinnah had to tell the court. He was straight and forthright, and always left a strong impression whether his case was intrinsically good or bad. I remember sometimes at a conference he would tell the solicitor that his case was hopeless, but when he went to the court he fought like a tiger, and almost made me believe that he had changed his opinion. Whenever I talked to him afterwards about it, he would say that it was the duty of an advocate, however bad the case might be, to do the best for his client". He reminisced that Jinnah's 'presentation of a case' was nothing less than a piece of art."
Jinnah appeared in the annual session of the All India Congress, Calcutta, 1906. Dadabhai Naoroji presided over the session with Jinnah serving as his secretary. In his speech Dadabhai called the partition of Bengal a "bad blunder for England" and addressed the growing distance between the Hindus and the Muslims in the aftermath of partition. He called for a thorough political union among the Indian people of all creeds and classes. "The thorough union, therefore, of all the people for their emancipation is an absolute necessity…They must sink or swim together. Without this union, all efforts will be vain."
Jinnah reiterated this call for national unity at every political meeting he attended in those years, and he emerged as true Ambassador of Hindu-Muslim unity. He met India's poetess Sarojini Naidu at that Calcutta Congress, who was instantly captivated by the stunning appearance and rare temperament of India's rising lawyer and upcoming politician.