Ricky Lightfoot was out on a fell run on Great Gable in the Lake District, UK, when he heard a sheep bleating from below.
Negotiating jagged rocks and carefully clambering down the steep slopes, the firefighter kept climbing until the lamb came into view.
Once the scared animal spotted the 31-year-old, it instantly ran away from the sheer drop it was stuck next to and over to Ricky.
Alternating between carrying it under his arms and leading the way, Ricky and the lamb slowly but surely began their 200metre climb back up the mountain.
Having spotted a flock of sheep, the lamb instantly re-joins the group, forgetting about its human saviour pretty quickly.
Ricky, from Dearham, Cumbria, said: “I was just on my way back from a long run and I heard some bleating but couldn’t see where it was coming from.
“I was just about to turn back for home when I heard it again.
“It seemed really strange that it was crying so loud and for so long, so I decided to go down.
“It took between 25 and 30 minutes to get down the path.
“It was rough for me to get down so I’ve no idea how the lamb ended up at the bottom.
“I could tell how happy it was to see me straight away as it didn’t try and escape.”
Ricky, who has been fell running for 16 years, was training on the mountains ahead of representing Great Britain in the World Mountain Running championships on June 18.
He added: “If nobody had saved it, I’ve no doubt it would have died.
“It was too small to climb that terrain again so it would certainly couldn’t have survived much longer.
“As soon as the lamb saw the other sheep it wanted nothing to do with me.
“I assume they were family as they accepted him into the flock right away.”
Ricky finished sixth in championships, with Great Britain finishing second overall.