Born in Kathmandu, in 1987, Paras Khadka first represented Nepal at the Under-15 level when he played in the Under-15 Asia Cup in the United Arab Emirates in December 2002. He played for the Nepal Under-19s the following year, playing once against India Under-19s, and also in the 2003 Youth Asia Cup in Karachi.

In 2004, after playing in the ACC Under-17 Cup in India, he played in his first Under-19 World Cup, the 2004 ICC Under-19 Cricket World Cup in Bangladesh. He also made his debut for the senior side that year when he played against Malaysia in the 2004 ICC Intercontinental Cup, also his first-class debut.

Later in the year, he played in the 2004 ACC Trophy in Kuala Lumpur in addition to ACC Fast Track Countries Tournament matches against Singapore, the UAE and Hong Kong. In early 2005, he played in the Repêchage Tournament of the 2005 ICC Trophy,

After a match in the 2005 ICC Intercontinental Cup against Hong Kong, he returned to the Nepal Under-19 team for the 2005 ACC Under-19 Cup, held in Nepal. Nepal won the tournament after beating Malaysia in the final, thus qualifying for the 2006 ICC Under-19 Cricket World Cup in Sri Lanka the following February. Nepal won the plate tournament in the World Cup, beating Test-playing nations New Zealand and South Africa along the way.

Returning to the senior side, Khadka went on a tour of Pakistan before playing in the 2006 ACC Trophy in Kuala Lumpur. He also played all four ACC Premier League matches against Hong Kong, the UAE, Singapore and Malaysia that year. He played in the 2007 ACC Under-19 Cup in Kuala Lumpur, which Nepal again won after beating Afghanistan in the final.