The 22-year-old lost consciousness before hitting the ground at Allianz Park and ten minutes passed before he was removed from the pitch.
However Saracens director of rugby Mark McCall eased fears after the final whistle that Farrell had sustained any serious damage.
"Owen has a bang on the head and will go through the normal protocols, but is fine," McCall said.
"We're really pleased with the performance in both halves. Overall every area of our game was very good."
Farrell had kicked three penalties and two conversions, as Saracens stormed to a 49-10 win, while fellow Lion Billy Vunipola crossed the whitewash to score one of the hosts' six tries.