Maierhofer was initially trained as a restaurant specialist/cook. The tall
striker joined
Bayern Munich's
reserve team from Austrian side SV Langenrohr in July 2005, and signed a professional contract with the club one year later, eventually making two
Bundesliga appearances as a late
substitute, during
2006–07. In two seasons with Bayern Munich's reserve team, he scored 21 goals in 42
Regionalliga appearances and was the team's top goalscorer in both seasons. In January 2007, Maierhofer moved to
2. Bundesliga side
TuS Koblenz until the end of the season, scoring three goals in 14 league appearances. In July 2007, he signed a two-year contract with another team in the division,
SpVgg Greuther Fürth, but the club sent him on a six-month loan to
Austrian Bundesliga's
Rapid Wien in January 2008. He helped Rapid win the
2008 Bundesliga title, after scoring seven goals in 11 league matches for the club, including braces in a 2–0
derby win over
Austria Wien and a 7–0 away win against the club's main title rivals
Red Bull Salzburg. Consequently, Rapid decided to make the deal permanent and signed Maierhofer on a three-year contract. The 2008–09 season saw his best goalscoring return as he struck 27 goals, including two in
Champions League qualifiers, helping the club end the league campaign as runners-up. He signed for newly promoted
Premier League side
Wolverhampton Wanderers in a three-year deal for an undisclosed fee – reportedly an initial £1.8m – on 31 August 2009. He scored on his debut in a 3–1 defeat at
Blackburn Rovers. He suffered a hernia injury which put him out of action for several months, and upon regaining fitness was no longer in contention at Wolves. He was instead sent on a one-month loan to
Championship club
Bristol City in March 2010, but failed to make an impact. During summer 2010, he was told he was no longer part of Wolves manager
Mick McCarthy's plans and was instead loaned to 2. Bundesliga club
MSV Duisburg on a season-long loan for the
2010–11 campaign. He scored 12 goals during the season, including a goal in a
DFB Cup semi final to take the Zebras to
the final where they lost to
Schalke. On 23 August 2011, Maierhofer returned to Austria when he signed for Red Bull Salzburg in a two-year deal. After a year and a half in Salzburg, Maierhofer returned to Germany, signing for
1. FC Köln in January 2013, but left in the summer. On 14 March 2014, Maierhofer joined
Championship side
Millwall on a short-term deal until the end of the
2013–14 season. On 19 November 2014, he signed a short-term deal with
SC Wiener Neustadt of the
Austrian Bundesliga for the rest of 2014. He was part of the starting XI against
Wolfsberger AC three days later and scored the first goal in a 2–0 home win. On 12 February 2016, he signed half-year contract with option to buy with
FK AS Trenčín. ==International career==