That topped a consensus estimate of 6.7 percent year-over-year growth for the quarter, marking the third-straight quarter of 6.8 percent growth for the world's second-largest economy.
Although the headline figure signals a strong start to the year for China, there will be a "roll down in growth going forward," said David Fernandez, chief Asia Pacific economist at Barclays.
That is as real estate investment is expected to moderate as the government aims to curb excessive speculation in the sector, Fernandez told CNBC.
Beijing is also cracking down on environmental pollution from industry.
The latest figures may confirm that's occurring, with March industrial output growth slowing to 6 percent from a year ago, compared to the 7.2 percent for the January through February period.
In other data, January to March fixed asset investment growth slowed to 7.5 percent from a year ago, down from 7.9 percent in the first two months of the year. Economists had expected fixed asset investment to come in at 7.6 percent over the first three months of 2018.
However, retail sales beat expectations in March, rising 10.1 percent from a year ago, beating the consensus forecast of 9.9 percent.