Rajoy and Chinese Prime Minister Li Keqiang signed more than 10 deals worth over $4 billion, Li told reporters at the Great Hall of the People. Details on the agreements were not immediately available.
"This indicates that the economic cooperation between China and Spain is effective and has huge potential," Li said.
"Spain is an influential European country," he added. "We hope to strengthen our relationship with the EU through our relationship with Spain."
Rajoy noted Spain's "very difficult economic moments" over the past few years but added that country's second-quarter growth was the fastest of any in the Euro region.
"This is encouraging and offers a great opportunity," he said. "I hope this is a starting point to further economic development."
Spain's third-largest source for imports is China, after Germany and France, with mobile phones and apparel comprising about half that amount, according to Rajoy's office.
By contrast, China is Spain's 13th leading export client, and its 17th leading destination for investment, Rajoy's office said.
Asked Thursday about the trade imbalance between the two, a Chinese foreign ministry spokeswoman maintained that China "has never intentionally sought a trade surplus".
"We are willing to improve our bilateral trade between China and Spain," spokeswoman Hua Chunying said. "So I believe that through this visit, the leaders will hold discussions including on improved trade ties between the two countries."
Rajoy is expected to meet Friday with Chinese President Xi Jinping as well as with the heads of leading Spanish companies in China.
As China's economy has boomed, so too has the number of its citizens traveling abroad, and Li said that Beijing hopes Rajoy "could significantly reduce the time it takes for Chinese nationals to obtain visas".
"This will help the two countries' citizens to nurture friendship and offer more convenience," he said.
Relations between Spain and China wobbled early in 2014 when a Spanish judge sought international arrest warrants for former Chinese President Jiang Zemin and four other top Chinese officials as part of a probe into alleged genocide in Tibet.
The case against the Chinese officials was brought by the rights groups under Spain's recognition of "universal jurisdiction", a doctrine that allows judges to try certain cases of human rights abuses committed in other countries.
Within ten days, the Spanish parliament voted to scrap this provision, announcing it would shelve several high profile international cases including Tibet-focussed investigations.
Spain's major opposition party, the socialist PSOE abstained from that vote and slammed the move, saying the government had bowed to pressure from China.