Rates have been creeping up since last summer and are now at their highest level since November 2019, according to Moneyfacts.
The average two-year fix has jumped from 2.51 per cent in May 2020 to 2.92 per cent today.
And the typical five-year fix has increased from 2.94 per cent to 3.29 per cent over the same time period.
It means now could be a good time for investors to consider their options, Moneyfacts said.
The good news is that the number of landlord mortgages on offer is at its highest level since March 2020, though product numbers are still not back to pre-crisis levels.
There are currently 1,976 buy-to-let mortgages on offer, from lows of 1,455 in May 2020.
However, this is still some way below the 2,897 products available in March last year.
The number of 80 per cent loan to value (LTV) mortgages has increased five-fold since May when just 19 products were on the market. In the last month alone a further 26 deals have been added at this level taking the total to 100.
Eleanor Williams, spokeswoman at Moneyfacts, said: “Following an overall increase of 158 since December, there are now 1,976 BTL products on offer, with growth being seen across nearly all the LTV tiers.
“It is especially positive for landlords with lower levels of deposit or equity, as this growth has extended to the slightly higher-risk 80 per cent LTV bracket.
“Here, an increase of 26 deals since December could be an indication that despite the still uncertain economic outlook, BTL mortgage providers are keen to cater to these customers.”
She also add a word of caution, noting the data showed the market had remained volatile since the start of the New Year.
“Lenders have been adjusting their offerings and consequently availability continues to fluctuate,” Williams added.
“There are now 27 fewer mortgage products on offer than there were just a couple of weeks ago, and so those considering exploring a new BTL mortgage could do well to secure the knowledge and advice of a qualified adviser, to ensure they keep abreast of any relevant changes.”