Westerhof originally joined Chivas de Guadalajara in 2003 to oversee the club's youth teams, but took over as head coach of the first team in October of that year. He stepped down as coach after the Clausura 2004 season. On 3 June 2005, Guadalajara's "sister" team, Chivas USA, named Westerhof its head coach, after a disastrous start under Thomas Rongen. He was replaced after the season by Bob Bradley and then came back to the parent club as its head coach.
Besides coaching, he has been a teacher in Heerenveen (the Netherlands) at the Central Institute for Sports Education (CIOS) for many years. For Apertura 2007, Westerhof was appointed New Head Coach of Necaxa of Mexico.
On 12 June 2008 Hans was appointed Vitesse new coach. He was then sacked after 6 months in December after a disappointing first half of the season. Having led them into 15th position of the 18-team league, he managed 15 points from 17 matches.