The New York-based firm said it earned $819 million, or $2.96 per share, excluding certain expenses, compared with $727 million, or $2.40 per share, a year earlier.
Investors added a net $34.7 billion to BlackRock's long-term bond, stock and alternative funds in the quarter, while withdrawing $24.4 billion from cash management accounts and $4.5 billion from advisory accounts.
Assets under management rose to $3.65 trillion, bolstered by rising global markets. The Standard & Poor's 500 index, for example, gained almost 16 percent for the 12 months ended March 31.
Shares of BlackRock closed up $1.69 to $193.72 on the New York Stock Exchange on Wednesday. The shares have declined 4.7 percent over the past year.
(Reporting by Aaron Pressman; editing by John Wallace)