In his youth Per-Olov Ericsson competed in ice hockey and skiing before finding success in the swimming pool representing SK Neptun in Stockholm. During the late 1950s and early 1960s Ericsson won multiple medals in relay races at the Swedish swimming championships. From 1958 to 1961 he won four consecutive golds in both the 4 x 200 metres freestyle (long course) and the 4 x 100 metres freestyle (short course). His performances earned him a place at the 1960 Roma Olympics where he came 22nd in the 400 metres freestyle. Ericsson was a good all-round athlete who could have also represented Sweden at the Roma Olympics in the modern pentathlon. He was also an excellent water polo player, competing in 67 international matches during his career.