Corn also firmed as traders anticipated the grain would be among the goods next on Beijing's shopping list following recent goodwill purchases of US soybeans over the past month.
Wheat rose for a fifth straight session as rising prices in rival exporting countries such as Russia stoked expectations of a pickup in demand for US shipments.
Spillover support from sharply higher crude oil prices and a weaker greenback, which makes dollar-denominated goods more attractive to buyers holding other currencies, offered further support to grains.
The market focused on positive comments from US officials after three days of talks in Beijing.
The US Trade Representative's office said on Wednesday that China had pledged to purchase "a substantial amount" of agricultural, energy and manufactured goods and services from the United States.
"There were some good comments from the trade talks ... There's a continued underlying sense of support in the market as long as trade tensions are not blowing up," said Rich Nelson, chief strategist with Allendale Inc.
China earlier this week approved five genetically-modified crops for import, the first in about 18 months, and booked another wave of US soybean deals after effectively freezing purchases last summer.
Adverse weather in top soybean exporter Brazil provided further support to prices.
Consultancy AgRural slashed its Brazilian soy crop estimate on Wednesday to 116.9 million tonnes, from 121.4 million previously, citing poor weather in southern Brazil.
Chicago Board of Trade (CBOT) March soybeans rose 5-1/2 cents to $9.24 a bushel, while March corn gained 2 cents to $3.82 a bushel.
CBOT March wheat rose 2-1/4 cents to $5.20 a bushel after nearing a three-week peak of $5.24-1/2 notched a day earlier.
Wheat support stemmed from accelerated demand in the global marketplace, with rising Russian prices offering US exporters an opportunity to capture sales.
But disappointment over Egypt's purchase of only Russian wheat in a snap tender pared futures gains near the close. US wheat was offered at competitive prices in the tender, but the high cost of freight from the United States proved prohibitive.
Other recent global wheat business included purchases by Algeria, Taiwan and Tunisia.