His championship point left him in 19th position overall in the Formula Renault 3.5 class, the highlight of the season undoubtedly his win at Donington Park last month.
Walker had a tough time qualifying in Spain on Saturday morning, finishing 12th in his group.
He reported back that it felt as though the engine was cutting out so he was unable to push.
He then got a good start in Saturday’s race, driving through the middle of the pack on the long drag down Barcelona’s pit straight to move up to 21st position.
He eventually finished in 15th place, which was an eight-place improvement on his starting position.
Walker set himself a top-ten finish in Sunday’s race and despite being shunted from behind, he achieved his target.
The shunt did not give him any terminal damage and he proceeded to drive well in front of the 90,000 spectators at the Circuit de Catalunya.
Walker said: ‘I was relieved that the car was okay after I was hit at the start, because it was good hard hit.
The car actually felt very good and I had a great time racing.
‘Our aim this year was to win a race in our first season and we achieved that, before going on to score points in the remaining races.
‘The World Series is a fantastically run championship and next year, with the new cars coming, it will be even better.
‘It’s a great place to learn and I’m already looking forward to next year.’ Walker is supported by Horizon Group and ASL.