The 69-year-old man was cut free from his white Ford Transit van after the collision on the southbound carriageway at Cilfynydd at 12:25 BST.
The Wales Air Ambulance was called and the road was closed in both directions, causing delays between the Abercynon roundabout and Pontypridd town centre.
The man is in a "stable condition".
The northbound carriageway of the A470 re-opened at about 14:05 while the southbound lanes opened at about 18:20.
A man is in hospital with serious injuries following a crash between a lorry and a van on the A470 in Rhondda Cynon Taff.