He began his professional career in 1993 with the Low-A Boise Hawks as a second baseman and outfielder and hit .298 in 35 games.

Guiel had a breakout season with Midland in 1997 as he was converted to a full-time outfielder and batted .329 with 22 home runs and 85 RBI.

He then spent two months playing for the Oaxaca Warriors in the Mexican League before being signed by the Kansas City Royals on June 13.

After re-signing with the Royals in 2002 and hitting .353 with Omaha, he was called up to the major leagues and made his debut on June 22, striking out in his only at-bat.

For the 2007 season, Guiel signed with the Tokyo Yakult Swallows of Japan's Central League, hitting 35 home runs with 79 RBI.

His ouendan theme during his time with the Tokyo Yakult Swallows is set to the Canadian national anthem, O Canada.