His brother Santiago "Aguaviva" Senillosa, is also an important rugby player.
Senillosa made his debut for the national side on April 28, 2002, in a match against Uruguay, and has received 30 caps in total, scoring 128 points (as of September 23, 2007). Senillosa was in the Argentine squad for the 2003 and 2007Rugby World Cups, where he has made 4 appearance in total.
He played all of his amateur sport life as a centre in the Hindu Club. In December 2010, he was suspended by 52 weeks, after a semi-final of the Top 14, in a game with La Plata Rugby Club, after altercations with the referee. He returned to competition afterwards but faced a serious injury upon his comeback. In March 2013, he announced his return to action once again, after an operation.