Richard Leonard, one of two candidates hoping to replace Kezia Dugdale, said the UK Labour leader had “revitalised the party and energised young people” since taking charge in 2015.
Mr Corbyn’s first year in the top job was marked by several high-profile resignations among his frontbench team and a subsequent leadership challenge in from Owen Smith.
But at June’s snap election Labour increased their share of the popular vote to 40 per cent, resulting in a net gain of 30 seats - including six gains in Scotland.
In a column for the Labour List website, Mr Leonard argued this progress would not have happened if Corbyn had been forced from office in September 2016.
“Last year, when times were tougher, many called on Jeremy to quit but I was proud to be one of those who stood by him and backed his leadership – because I believed the members’ judgement in electing him was right, and because I saw that his authentic and principled politics had the capacity to change politics for the better,” he said.
“It is necessary to be consistent, and pursue real unity if we are to win.
“It would have been a disaster if Jeremy had been forced out last year. The gains we made in the general election across the country, including real, if insufficient, progress here in Scotland presage victories to come. This would not have happened if the party had broken from the path of renewal that Jeremy represents.”
Mr Leonard is in a race with fellow MSP Anas Sarwar to become the next leader of Scottish Labour. The contest was triggered by the surprise resignation of Kezia Dugdale last month. Both candidates launched their respective campaigns at the weekend.
While Mr Sarwar, a former MP and previous deputy Scottish Labour leader, is seen as being in the moderate wing of the party, Mr Leonard is more to the left and closer politically to UK leader Jeremy Corbyn.
The result of the contest will be announced in November.