The Chinese government has signed several agreements worth $46bn, focusing on building a China-Pakistan Economic Corridor (CPEC), a network of roads, railway and pipelines between the two countries.
When completed, the superhighway will give China direct access to the Indian Ocean.
"Pakistan, for China, is now of pivotal importance. This has to succeed and be seen to succeed," Reuters quoted Mushahid Hussain Sayed, chairman of the Pakistani parliament's defence committee, as saying.
The investment is almost three times the entire foreign direct investment Pakistan has received since 2008, according to BBC correspondent M Ilyas Khan.
The road will pass through Pakistan's restive Balochistan province, where local Baloch are fighting the Pakistani army for self-rule. Pakistan has vowed to crush the insurgency.