In keeping with Francis's tendency to eschew much of the pomp and ceremony associated with his role, the anniversary was not marked in any official way, with the exception a solitary tweet from the official @Pontifex account.
"Please pray for me," the 77-year-old wrote to his 12 million followers in nine languages, echoing an appeal he made in his first address to followers from the balcony of St Peter's Basilica exactly one year ago.
He left the Vatican on Sunday after his weekly blessing and will return on Saturday.
During his weekly Angelus blessing of the faithful in Saint Peter's square last Sunday, he urged believers to resist temptation.
The Lenten retreat is a regular fixture in the Vatican calendar and its focus on self-denial, penance and repentance chimes with the tone Francis has set for his papacy through his emphasis on the themes of mercy, humility and support for the poor.
"Portraying the pope as a kind of superman, a type of star, it seems offensive," Francis recently told Italian daily Corriere della Sera.
French Vatican expert Frederic Mounier, who has just published a book entitled "The Vatican Spring", added: "The same media that builds him up into an adored icon could just as easily end up trying to lynch him."
More than anything, the pope's first year in office has been marked by his apparently sincere determination to maintain the kind of simple lifestyle the former Jorge Mario Bergoglio has had throughout his career as a priest.
