The bank made 2.27 billion riyals in the three months to September 30, up from 2.01 billion riyals in the same period a year earlier, it said in a bourse statement.
Four analysts surveyed by Reuters had on average forecast quarterly profit would be 2.21 billion riyals.
Al Rajhi has now posted profit growth for eight straight quarters.
It attributed the latest performance to a 4 percent rise in income from financing and investments and a 2.2 percent climb in fees from banking services.
Total operating expenses fell by 8.4 percent as impairment charges for financing and salaries dropped.
Loans and advances at the end of September stood at 233.2 billion riyals, up 3.2 percent on the same point of 2016, while deposits dipped 1 percent to 270.1 billion riyals over the same period.
Despite tepid economic conditions, analysts expect Saudi banks to benefit from an improvement in liquidity and credit growth in the coming quarters after the government cleared much of the outstanding payments owed to the private sector.